I think a problem with the whole "bland leaders and uninspired quotes" is that the game is trying really hard to capture the uniqueness of Alpha Centauri, but you can't just recreate inspiration on demand.
I keep seeing this notion brought up, and I keep having to wonder if that's actually what they were going for, or if people are just seeing enough similarity to hope followed by enough difference to despair. I mean, nobody calls out post-AC Civ games for "trying to differentiate factions AC-style and failing." Is that because they weren't but BE is, or because BE looks close enough to AC to disappoint people hoping for a direct sequel?
Firaxis put so much work into the quotes in SMAC's tech tree, having the quotes in it add to the character of the faction leaders, that for me at least, it did make the Civ games pale in comparison. I just didn't figure it was fair to expect them to do the same thing for historical leaders with historical technologies. It seems like it would require considerably more effort to do all that historical digging to find appropriate quotes for the technologies and so forth by the actual historical leaders, as opposed to just making stuff up. Civ BE, on the other hand, doesn't have historical leaders or historical technologies.
I'd also compare how there were a variety of different policy choices on which the factions could differ in SMAC, as well as motivations for the leaders. Not having played CivBE I don't know how this works out in it, but in Civ V with both expansions you no longer had policy choices which you could change, just perk trees, religion, and a simplified ideology choice (Freedom, order, or autocracy), which determined which ideology perk tree you used (and divided the world into nations which followed the same idology and liked you for it, and nations which didn't and disliked you for it).
If you look here, for instance:
http://alphacentauri2.info/wiki/Gaia%E2%80%99s_StepdaughtersYou see that leaders have a personality / willingness to use force (Deidre is Pacifist), interests which determines what area of research they prefer to focus on (Explore), a particular social value that they try to maximize (Planet), an ideology / preferred social choice (Green), anti-ideology which they cannot take (and get upset if others take) (Free Market), which all combines to contribute to their personalities.
The leaders in SMAC all felt like they had their own personalities and I'd wager that this as well as the quotes from them both played large parts in it.