I guess this is the question. Which would you rather have for the 'important' civs. Strong UU/UB with non-optimal traits or Strong traits with medicore UU's.
Currently the 'important' civilizations have strong UU's usually[Roman Praetorian, Byzantine Cataphract, England's Redcoat, and Eqypts War Chariots are a good example]. In addition few have poor traits. True Rome has the Imperialistic[for those of you that really dislike it] but they have industrious and organized as secondaries, both of which are very useful. Actually Imperialistic + Organized + Mining as a starting tech is good for Rexing.
And actually Persia[which ranks as an important civ in my book] has both a strong UU and strong trait combos. Just about the only thing 'weak' about them is the UB... and I even like that quite a bit.
So again I ask... would you rather have strong UU's/UB's or a good trait combo. As Rome shows a strong UU can make your traits fairly redundant. After all, they certainly don't need aggressive or charismatic.