Aspen's Worlds of Aspen are previews and samples, as far as I can tell. Then again, the DC ones are either free issues - or previews and samples. Marvel gives us new short stories, two per issue, and other companies do any of these things. My point is that previews and samples aren't unheard of, and I know that I might get them in these freebies. Then again, I'm not disillusioned: Free Comic Book Day is not only a celebration of the love of comics, and a way to give back to the fans, but also something that the companies are using to try and sell more comics.
I've come to think of Aspen's FCBD like the samples at Trader Joe's. I might like what I get, and I might not, but I appreciate the free taste so I know what I'm buying. (Or not buying.) It's free, so I can't really find it in me to begrudge them choosing what to sample, and I know I'll be buying, well, more of the same, but I'm also usually happy to try something new.
Which is why I'm happy to read these, even when I won't continue on with the series. Damsels in Excess is a good example: I like the eventual reveal, the premise of this series, but its' also done like a princess reality show. And I'm not a reality show person. The execution is actually quite clever, but it's also something I don't enjoy. Since I'm getting into this publisher, I like knowing what I enjoy and what I don't. (And it's not possible for one publisher to pander exclusively to one person, or for one person to enjoy 100% of what they publish because of that first fact. I don't expect to love everything Aspen puts out, but this helps me decide what to continue with.)
I think I will follow up on Zoohunters, though. I love the main character, an interstellar poacher who has morals. She will get the animals, but not harm them in the process. When she sees an animal being abused by another poacher, she decides to buy it, even though the price is... bizarre.
I also like the world: it looks like a fun, space opera type adventure, and I had enough fun with the sample that I want to continue.