Some people use this if they ran out of novels to read. If the synopsis is good enough, they will start reading.
Maybe random button under certain criterias? I'm sure it would get boring to click and get novels with only a few chapters or that have things you don't like. Criterias (conditions) would help restrict the kind of novels you want whilst also not letting the things you don't want to pass through the filter. Even then, I'm not sure it's necessary. There aren't that much novel if you're interested in a specific genre. I think that feature would become more interesting as more novels come out (and releases ofc).
I like your suggestion there. Make the criterias optional. Yeah, it is not necessary but it can also lead you to enjoy other genre. Back when I was reading manga/before I transitioned into reading novels 100%, I used the random button whenever I don't have anything to read. From this, I was able to read Shoujo even though I don't prefer that genre.
This idea would be pretty good. would make my reading list grow even more.. muahaha... I also gotta get around to reviewing a lot more stuff.. hmm
If you want the random button to filter by certain criterias, then Series Finder does all the same with some extra steps. Just add your filters, think of a random number and find it from search results.