It's not that some types of comics are ok to pay for and others aren't; it's the difference between putting up a paywall between readers and content and letting readers pay you if they like what you're doing. I like that model better because Snarlbear isn't my full time job and I'm not planning on making it my sole source of income. If people like what I'm doing and want to give me money, that's awesome! But I also like having my comic out there for people to read or for future employers to browse through (my current comics job I got from someone who found and was interested in my webcomic).
Basically, for this particular project, I am more interested in people actually reading it than getting a few people to buy the ability to read it.
If I wanted to monetize my comic fully I would do so myself via pitching current issues around to publishers and putting up ads on my main site. HOWEVER, Snarlbear has always been kind of an awkward learning comic so I don't think it could go to published print without some serious editing/redraws on the earlier chapters and I don't want to stop and go back. I'm super busy and I love that Tapastic wants to help us out with the difficulties of turning pages into dollars and making our work into -professional product materials-. I just have concerns about how that is done.
P.S. E-comic sales are definitely a thing outside of porn and they're awesome (comixology is the big one I think, plus stuff gettin sold on gumroad)! I actually might go that route in the future depending on what I even end up doing with my career. Just...not with Snarlbear in its current form. I might do a gumroad pdf download with some extras when it's all done but that's a bridge I'll cross when I get there
Edit: tl;dr - I love that tapastic is helping me get paid but I want my comic to stay free so more people can read it