[RX-78GP04G Gerbera]

I think they manage to flesh things out quite a bit. After all, it's been about 15-16 or so episodes for each generation (the series itself totaling at 50 episodes).

Sure we don't know virtually everything about each main character or others, but after UC (which did explain a lot, even if after Mobile Suit Gundam and such), you learn that we don't need to know SO much besides what's necessary as the focus is on the characters at present. Until Kio's character plays out to the end, Asemu seems to have turned out better than Flit given how different he is in pretty much every way in the end (wanting to understand the Vagan rather than exterminate them, not being a powerful X-Rounder, but instead becoming just a very good pilot, and so on), thus allowing for a different route in development.

Sadly, that's something Wing, SEED and SEED Destiny lacked a lot of. 00 had it, but it felt like the characters at the present didn't really change a whole lot in exchange.

Unfortunately, that's what the trade-offs tend to be, especially if you only spend 1-2 official series in that specific universe; something the Universal Century has a huge advantage in compared to other series (10 official series in the Universal Century era alone; MSG, 08th MS Team, 0080, 0083, Z, ZZ, CCA, Unicorn, F91, and Victory), allowing for more extra content to come out and all and/or ways to connect them (0083, for instance, being more about the link between the development of MSG to Zeta).