I've been playing for a while now (vanilla and various mods over the years) and I can say with 100% certainty that the game in it's vanilla state (yes, without any third party programs) is playable. Are there a few features that are buggier than they could be? Of course.. However they all work well enough.
I give myself a variety of challenges to make the game more difficult including using solely the military for defense (no walls or traps) and still manage to use them for an effective defense without using any third party programs or the danger room (or any other) exploit.
Suggesting the game is unplayable, to me, means that either you have an incredibly high standard of what a playable game is, aren't very good at the game, or haven't been playing it very long.
Now, that said, I do agree that I'd prefer more frequently updates with less content than very infrequent updates with lots of content; it would allow for more testing by the community as we go rather than a huge amount dumped on us all at once. In addition I agree that I would like to see some bugs get ironed out more frequently than they are. As somebody who likes to use the military and (as a result) the hospital I would like to see both of those work better (even if the claims that they are completely broken are simply not true), as well as various other things.
Lastly, I'm amused at the idea that if you don't personally pay somebody for a product it's somehow inappropriate for you to make suggestions (or, gasp, even complain about it). I think I get it, from a really basic level; if I give you a free sandwich I don't want to hear that you'd have preferred turkey over ham. That said part of the implied purpose of us as fans is to help improve the game, we have acted as effectively alpha and beta testers for years now (over a decade in fact if I'm not mistaken) and while of course we should be respectful when talking to anybody if all we did was say "Game is great, keep doing your thang!" we wouldn't be doing much good.
However, if it makes people with the mentality of "you didn't pay for it! you don't get to complain!" feel better, I have donated before.. That said, it was a donation, I didn't not give it expecting anything (though the drawing was nice). But I don't think there is anything wrong with commenting on a piece of public art. In fact, I think by posting the game on the internet and creating a forum toady is implicitly allowing and encouraging these types of conversations. If he didn't want any feedback (which includes positive and negative) it was a mistake to create a forum for discussion.