Just a couple of points I want to make here.
You draw parallels between the expense of modifying a costume, with that of modifying a base. Yes, costume changes are expensive, but they do not contain a recurring cost. How would you like it (thinking as a player now) if there was a recurring cost every few weeks for that helmet that just perfectly fits the concept of your character?
Similarly, you point out (rightfully) that often, one person in a SG decides upon a uniform, and no one in the SG complains when they must dedicate one of their costume slots to that costume. I don't feel constrained by creating a SG costume, because I know that I will eventually have 3 additional costume slots on my character that I can customize to my heart's content.
So, on a supergroup of 20 characters, there are a total of 80 (or 100, if you allow the extra "Halloween" costume) possible costume slots. One-quarter (or one-fifth) of those are consumed by a dedicated SG uniform; three-quarters (or 4/5ths) of those costumes are left to the creativity of the individual player.
That same supergroup will have one base. That one base will be dedicated specifically to the needs of the supergroup, and often, a single architect will wield total control. So, while all 20 members of the SG can utilize the base, only one person out of 20 actually feels ownership of the base and can internalize it to their character.
I really think that we need to draw a clear separation in use and expectation when it comes to bases. By and large, users equating bases with the equivalent to a personal lair are going to be disappointed; a small minority of users are going to have editing control, and even those that do, must work within resource guidelines. Users equating bases with an opportunity to power game a little bit, and raid other SGs in a friendly and competitive manner, are going to love them, especially if they have control.
I feel that it is time that we recognize that the Base system, as it is designed and as it exists, is not there for the "socializer" aspect of the community. It doesn't serve this need, nor will it ever serve this need. Instead, some of the technology that is there can probably be carried over to a "lair" setup, which neither the cost of bases, nor their gameplay benefits. Instead, these would avoid the cost and scarcity issues of bases, while providing users a similar level of customization.
I would suggest something like a single room "lair" opening at level 10, with additional rooms being added (with no recurring cost) at later levels, but I fear I've gone on well past what the majority of users will read.
Trying to come up with some good combat shots of them was starting to get fun. 