@Vinraith
That does make sense, and I think we're on the same page about what the end effect should be, even if there is some question of the means. But I think you've not looked closely at some of the guard posts. Some of them, like the warp counter-attack guard post, create a whole new defensive challenge for players never seen before here. Basically, a warp-style wave anywhere on the map with low warning. And for players who try to rush things like the command station, if that's all the strength they have to do, there are defensive challenges with the new AI Barracks, too.
I haven't said much about this, but one thing that I'm working on focusing on is trying to make the players have to spread their fleets out more for offensive and defensive purposes, or to make it a gamble when they concentrate their forces too much. I suppose I've only gone a little way down that road, but that is something I've been thinking about, as well.
When you combine this with the stuff that Keith has been doing with the hybrids, I think that's really a potent mix, but I want to do some more stuff in the base game, too -- thanks for reminding me, incidentally. I think a lot of it comes down to a risk/reward cycle with this stuff on the AI planets. Even a month ago, if there were 4000 or 5000 ships on an AI planet, so what? Aside from a slight bit of border aggression, or maybe a CPA risk, that simply wasn't much of a concern unless you needed to go through that planet: and then the risk came from if you went about attacking that planet incorrectly, you risked losing via the retaliatory attack.
If anything, I'm trying to make the risk of retaliatory attacks greater, because that's interesting to me and in keeping with the "equal and opposite reactions" type of approach we have here. I think that the warp counter-attack guard posts alone will negate some of the "sole bottleneck killing field" strategies that players have been getting used to, which I think can only be a good thing. It's the AI equivalent of transporting units across a few hops, but without removing the tempo from the human player (unlike the Warp Jumper AI type in CoN).
In my opinion, the mobility of a structure has nothing to do with it -- it's what happens when you engage that structure, and what the consequences of losing (or winning, or ignoring) that structure are to the larger game map. Since fixed structures are perfectly capable of launching cross-planet effects (going all the way back to the warp gates, but even more recently including raid engines, etc), I think those help to increase the challenge and make the risk of losing greater than it ever has been.
That said, just the few mechanics that I've put in so far probably are not enough to really accomplish what I (and, from the sound of things, you) want; I really should make it a priority for this week to add in a bit more of that.
Another way to put it is this: I think your concern is that the AI is losing its ability to direct force in potentially game-ending ways. That has been one of my number one concerns for the entire life of the game, and has been the genesis behind many of my changes and additions (CPAs, border aggression, you name it: all motivated by that). In my view, just cranking up the ship cap and letting the AI overrun the players if the players try to grab the command station wasn't cutting it -- it was too easy for the players to find a good bottleneck planet on the map, and it was also just as easy for them to go around to each guard post, killing all the AI ships as they did, with just the overflow from the wormhole guard posts posing any threat of overrunning at the end (and with any halfway decent bottleneck, that risk was minimal).
So I've been seriously scaling back the performance-affecting, grind-causing style of having bulk AI ships, and instead have been focusing on new mechanics that would let the AIs use warp at certain player-controlled times in order to create a more interesting overrun effect that requires some level of defense-in-depth. Even with just the counterattack guard posts that are currently there, you still have to have some form of defense in depth even though those are pretty rare; and that right there hampers the ability of players to create a good bottleneck planet, which in turn makes CPAs and waves more of a risk without actually making them any tougher directly, and so on.
It's a whole little ecosystem I'm trying to get going there, but the question is whether or not it is yet having the effect that I want. If not, then I think the solution is more clever new and different force-directing-from-afar mechanics, rather than just beefing up ship counts on the wrong side of the bottlenecks.
To be clear, feedback is very welcome, and if people want to post ideas about force-directing-from-afar mechanics based on what I've written in this post, then I'm all ears. I can't promise to do all or any of the suggestions, of course, depending on the programming difficulty involved, but I'd like to make that more varied than what I have done already and what I'm planning for soon. So ideas are welcome!