Well, let's see… 2kki has over 12 years, .flow is going to turn 10 next year. ib is from, what, 2011? What's next, towelket?
If the devs wanted to milk their cow, they would have done so already. It seems for some reason you associate popularity with success and if a game isn't… "available" to the west, then it isn't successful for you (and guess again, the eastern fanbase is x3 or x5 times the western one). If you want to help the developers, spread the word in your blog or among your friends. There's no need for them to be on steam. You don't really think any of the shitty games made in the west would really blast it on freem or any similar platform, right? Also there's the problem of localization, who do you think would translate them? Because the only translations are fan made and only when someone actually decides to sit their ass through the whole process of translating, scripting, testing and debugging. And don't expect japanese people to trust western faggots touching their game, it's happened in the past and hasn't gone well.
These communities have existed and done pretty well without messing with steam, and part of the fun is finding about them by yourself. And actually, people on steam do not appreciate RPGmaker games (and for a good fucking reason, tumblr has been spouting meme games for about 6 years and steam is full of fucking RTP graphics "games"), so don't think people will actually care about them and in fact be ready to see how people bash on the author because the dolphin raped a witch.