This a fairly big nut to crack in one reply.
To begin, we understand what you are saying, and there are days when we feel the way you must be feeling. You know, those days were you update and push to social media, don't make "Trending", stay on "Fresh" for only five minutes, and then get seemingly swept under the rug until your next update. 10+ hours of work on one page, gone in a moment. You watch your sub count actually decline because your update reminded some people to unsubscribe. Meanwhile some seemingly new creator out of no where posts only two one page episodes for a-gag-a-day (8 panels total) and receives a Staff Pick and a Daily Snack and just catapults up to 2K+ subs with a snap of the fingers. You're left wondering . . . whhhhaaaattttt. How's that fair?! It's not.
Unfortunately its just business.
The truth is that Tapas is a business and Tapas has to change in order to survive. Remember Inkblazers? Ultimately they couldn't stay open because they couldn't remain revenue neutral. The webcomics model is changing. Ad revenue continues to drastically decline. Tapastic had to find a new way to make ends meet and pay back their preferred shareholders.
Readers are constantly going more and more mobile with desktop users on the decline. Tapastic had to keep up with the times by building an app, one that likely cost well northwards of $500,000. We estimated in another post that their payroll is probably in the neighborhood of $50,000-60,000/mo. Ads aren't enough so they've gone into monitizing the reader base into purchasing Premium Content. First comics and now books.
Premium content is likely now the main source of revenue for Tapas, followed by their 15% tipping commission, and lastly ads. In order to stay in the green, Tapas is going to promote whatever generates the most income for them, which means the Premium Content. This explains why the Top Ten is the top ten. They likely also have metrics that measure which merchandise is selling and which series have the highest tipping activity and features them in the t-shirt banners and the tipping section.
As far as determining who gets a spotlight or a daily snack, a lot comes down to social media shares. Tapas wants to continuously grow its reader base. They know that for every X new readers they are going to sell X amount of Premium Content. If they feature something that ends up going viral on social media, most likely its going to draw new readers to the website or app. This is why gag-a-days are so popular for being featured. Humor sells, especially at 4 panels with a beginning middle and end, that takes less than thirty seconds to consume vs. a long form that requires a serious time investment on the reader's part and no quick laugh. This is also why content that is highly relevant gets featured. For example, back in July 2016 when Pokemon GO came out, if you did something related to it on Tapas, odds were you got a Daily Snack. Meanwhile if you create something that just doesn't seem like its going to get much attention, they aren't going to feature it. Tapas can only feature so many things each day and each feature they hand out is essentially a limited quantity valuable resource worth real money (tips/subs/Premium Content sales) so they're going to be selective on who gets a nod. Also series that they spent $10,000 back when Tapastic first opened as a bounty to attract big name creators are also going to get priority because there's an underlying investment the company wants to earn back.
It's not personal, it's just business. If your book you submit to be premium isn't going to be profitable after editing expenses, staff is going to reject. If your comic series doesn't come off as being something that is going to draw in new readers, it won't get featured.
We hate to see Tapas changing but it is the nature of the beast because publishing as a whole is changing. Hiveworks in its current state will probably not last. Ad revenue continues to decline and it has no mobile app. Webtoons oneday someday eventually has to make sense financially to LINE, otherwise there will be major changes there.
Tapas is just trying to get ahead of the ball because they see the writing on the wall. Currently their focus is to just keep growing as quickly as possible, which means sometime this year they will be adding open ebook publishing on the app. The goal there is to cut into Wattpad's huge readership (>2x Webtoons) and ramp up their own readership, then sell Premium Content to the new readers.
Most creators here, ourselves included, would LOVE for things to remain back in Tapastic, when things were a lot more relaxed and free and it seemed like creators had the run of the site. However that just can't continue because its not sustainable. So what we're seeing and what we're feeling is facing reality.
Staff time is increasingly becoming limited as they all have increasingly more tasks to do, so you may not get a reply.
We will do our best to quickly answer your seven bullet points:
1) Spotlights are based on what Tapas reader demographics are. Fantasy. Romance. LGTB. OR anything the content director deems highly sharable. As you point out, pretty art makes it highly sharable. OR highly relevant. Heroin use is up 145% since 2007. It's a topic that is commonly making the news.
2) Banners "never change" because they have to be hard coded in. Hard coding = time = money. Its less expensive to leave things static.
3) Sales metrics likely drive which shirt banners are present. If its selling the most, it's going to be shown. Also the banners are likely hard coded in as well. (See 2)
4) Trending is likely based on (Views + Likes + New Subs)/Old Subs over a period of one minute, with new subs having a much higher weight than likes, which is a much higher weight than views. If you have a bunch of subs that don't engage with your series, you won't trend, or if you have 10,000 subs but they trickle read over seven days, you won't trend because it has to happen in a short period of time.
5) Top 10 is for selling Premium Content. Premium Content sales from the top 10 likely heavily outweighs any revenue the actual top 10 generate via tipping and ad revenue.
6) Patreon would conflict with tipping. It's also directing traffic to go outside of Tapas. What for-profit business would want to direct traffic away from their site?
7) Can't answer this one since "quality content" is subjective. It would be great to see Tapas hire a community manager to try to engage with all of us on social media, answer forum posts, and make us feel valued. That used to be Michael's job, but he's so busy now with so many other things, he really can't do it any more. Tapas probably can't justify the cost in hiring a community manager either because of the cost/benefit analysis.
To close, we're not crazy happy about how Tapas is changing, but we realize that its just reality, and have to learn to accept the changes. All things considered it's the best game in town because:
A) its not gated so anyone can publish
B) offers mobile app reading
C) anyone can earn some income (tips+ad revenue)
D) there is a large readership already available for free if you can get their attention (Trending or a Staff Feature)
E) an excellent creator community
F) free hosting and no need to manage a website
G) Long term survival rate
There's not too many other options out there that meet all these criteria. . . if any.