I like getting them!! It's like collecting flair back in the super early facebook days. I don't really notice if an artist doesn't post them -- plenty still don't -- but I do enjoy them and think they're fun from artists who give them out!! :>
I do think it's good etiquette to make sure your thank-you isn't super vertically tall, though, since that can take up a lot of wall-space!
I've also found that there are some readers who normally wouldn't say anything that take thank-yous as an opportunity to comment on the comic or interact with the creator. One guy told me he'd been trying to work up the courage to ask me about a particular element of my comic, and when I left the thank-you he felt like that was a good chance to ask. For some, it's a way to make you feel more approachable, which I really like! (I'm very behind on my list right now, though I kind of like the idea of giving people time to read through and change their minds beforehand, haha!)
There's a few other threads about this if you want to get a general consensus (here's one, here's one, here's another). I read through a lot of them when deciding whether or not to make a thank-you myself, and was surprised to find the reception was overall really positive!! A couple folks expressed frustration with how Tapastic handles wall posts, which I can understand, so I always check every person's profile description to make sure there's not a note that they'd rather get those in a private message. ;u;
@digitalvalium1 It doesn't really matter who does or doesn't have time (tho once you get into the hundreds or thousands of subs, it eats up more time than you might expect!). The important part is that majority of folks here don't see it as a bad thing when artists don't post thank-yous. If you personally see it that way, that's up to you! But the idea that it gives that impression to most readers just isn't demonstrably true. A lot of readers (especially mobile folks) don't even know that they have a wall, and the majority of readers don't comment on thank-yous; just a few people do.
To most people here, it's a nice thing, but not a necessary thing. ;u; Every time anyone has asked "is it rude to not give these out?" on the forums, folks here have always assured them that it's perfectly fine to not join in; it's just a fun thing if you want to do it, and can be a cool way to for others to encounter your comic!