Next, a few points in response to various posts above:
1. There are two differences between using a golem and a fortress on deep defense (or a ton of turrets or whatever). First, the golems are way more powerful as a single entity, with way more health. This makes them far harder to kill.
Second, when it comes to all those turrets and fortresses, you wind up using up a ton of your ship cap on that one planet, rather than all over the place, which in turn costs you a lot of knowledge (one of the permanent resources. By contrast, golems cost you nothing permanent at this point, not even knowledge. The only possible permanent cost you could claim with them is the opportunity cost of not using them elsewhere, but that presupposes that you'll capture them as a matter of course as part of the game.
Oh, and I guess third, bombers and various AI ships have weaponry aimed at letting them occasionally take down a fort, whereas golems are specifically designed not to have those sorts of resources.
2. Part of the reason for making golems only function near AI warp gates is so that there is always the prospect of triple-size waves against them when they are not in enemy territory stirring up reinforcements instead. Those waves often will have a similar effect to the reinforcements, scattering from the planet and causing havoc elsewhere.
3. You guys convinced me on the offensive thing, the OMDs really already solve the problem I was then trying to solve with supply. So that's why that went away. Really, now golems are just all kinds of awesome, they can do everything most people would want to do with them, just not act as the ultimate camping defense.
4. Totally right on the sniper turrets being overpowered. Eventually I'll add leech turrets, but not right now (I should be on Tidalis, these set of changes in 3.168 took all of 10 minutes), and they likely won't be sniper-ranged, as that seems OP in general.
5. As part of the sniper changes, you'll notice the attack buffs, hopefully that will make them more useful on defense. It vastly increases their damage chance right at the start of an engagement, and doesn't affect their damage chance over a longer multi-minute engagement whatsoever. Also, they now feel more sniper-ish (rubikscube made a good comment that made me think along these lines), and reduce the amount of clutter and calculations going on during battles on AI worlds, at least slightly.
6. The fortress cluster penalty? Yeah, with so many fortresses possible now, and Buttons840 mentioning how those could be used somewhat exploitatively, that was inevitable, no?
7. RCIX, I also had thought about making golems dangerous to friendly ships, but that's just fraught with a lot of issues, I decided. But that was something I spent a lot of time thinking about yesterday, trying to find a model that would work, etc. In this case, I think simply removing the supply restriction handles the current issue well enough, anyhow.
Thanks for the thoughts, everyone. I'm going to be out a lot of today, but will respond when I can. Hopefully this solves most of the issues of serious contention, and this won't turn into some giant debate while I'm gone. Really, I feel like the golems are on pretty solid ground at the moment, and the snipers. But I guess we'll see what people think in practice!