Back in February, Valve released the source code for Team Fortress 2 (TF2) into the Source SDK, which allows modders to see how it all works and get their standalone mods onto Steam. But also, it allows them to fix up issues directly in Team Fortress 2.
If the fixes keep coming I might just get back into TF2. I first played it and got hooked through The Orange Box on the PS3 and then eventually on PC when i got a gaming laptop years later.
This leaves a sour taste in my mouth. Because the source code is not real open source, the contributors of those fixes have fewer rights to their own code than Valve. Valve should have just made the code proper open source. Keep the art assets proprietary, basically what id Software did when they were still cool. It's not like the Source 1 Engine contains great trade secrets after all those years since release and if it did, the non-commercial license would not keep snooping eyes away.
I would argue it's still better than keeping it closed though. It really is a half way mark. It allows those that do care and have the know how to actually fix the game they wanna play.
I highly doubt it'll lead to Valve selling copies, let alone a financially relevant amount. So it can't exactly be classified as exploitation either. Basically I think it's fine.
TF2 is free and has been for a while now. I don't see valve turning that around this late in the lifespan of the game. As far as multiplayer online games go, TF2 is geriatric, amazing it still holds such a large playerbase.
It does indirectly support the cosmetic market, from which Valve still makes money I think. It's kind of unfortunate that people work for free to support their income, but it's not worse than the game dying entirely, probably.