I think the concept of Thank You notes are great. Because there is no "post this picture or message on all of my subscriber's walls" option, it means that an individual creator had to spend time to post it on your wall. It's a kind gesture, but it can also come across as a promotional item. In a way it is, but isn't everything we're all doing here on the forums or on social media? If you have a decent comic, you want people to see it, right? So what's a better way to show yourself off than through a kind gesture towards a fan that also can lead interested people to your comic? In that case I would say the whole thing a very positive notion. Not all creators have this same kind of viewpoint, and sometimes a creator will have SO many subscribers that they have no time to do it, but sometimes they even post that thank you on THEIR wall in order for people to see it, just so that the gratitude is still there. (I'd rather have it on their wall rather than take up space in an episode anyways)
In other words, it's great that a lot of creators take their time to thank their followers. And that extra effort put in for posting a picture on your wall is a great gesture. If you think that it's just a marketing ploy or an excuse to promote yourself, I don't think that's really all that bad either. We all have to look out for each other and ourselves in this "business", and for the "clients" we have, a thank-you note is like a business card.
Of course, this is different than if someone posted a "hey check out my comic" link or something on my wall. That's a bit more negative.
