There's not a single thing I would like to see in FAF that involves changing the source code, except maybe fixing the sound bug. An entire new game with a better campaign, cutscenes, coop, all new units and factions, and everything could be made without the engine source code. The real important factor for me is that Sanctuary can actually make money, which means they could have regular tournaments and updates.
I don't think Sanctuary is a scam or anything. Just these type of things have a tendency to suck. PA had millions of dollars and an experienced team, but I couldn't play it more than a couple hours and then never touched it again. All the other similar games are even worse. I don't think it matters if they are paid employees or free volunteers, or if they use Unity or whatever. Creating the game today is significantly less difficult than it was in the early 2000's. You can find countless resources about everything you need to know and what the other games have done.