So, users get a feature-rich distribution platform, and developers (and by extension users) pay a tax to access those users. So the question is, how fair is that tax, and what effect does that tax have on the games that get made? Your view on that is going to depend on what you want from Steam, but more relevant I think is how much Steam costs to operate. How much of that 30% cut feeds back into Steam? My guess is not much; though I could be wrong.
But anyway, let’s imagine you took away half the 30% cut. Where does that money go? Well, one of two places: either your pocket, or the developers (or publishers) pocket (depending on how the change affects pricing). The benefits to your pocket are obvious, but what if developers just charge the same price? Well, as far as I’m aware, a lot of games are just not profitable - I read somewhere that for every 10 games, 7 fail, 2 break even, and 1 is a huge success - so my personal view is that this is an industry where developers need all the help they can get. If that extra 15% helps them stay afloat long enough to put out the next thing without selling their soul to Microsoft or Sony or whoever is buying up companies these days, and Steam isn’t severely negatively impacted, I’d call that a win.
Would you claim that devs who also port their game to console are guilty as the consoles also take 30% cut? The entire console scene is basically what Valve is doing, except valve decides to compete on an open platform instead of a walled garden.