Basically, i'm tired of (and i dont think i'm the only one) this system that most MMOs have of 'ooo, i leveled, time to get new gear cause my old stuff is now pretty worthless'.
With regards to weapons, instead of a slew of weapons which pretty much fill a limited number of roles, i would like to see one, maybe two weapons for each role. This sticks to what we've seen in previous fallouts, where you only had two real options for a sniper rifle (for example) the actual sniper rifle, and the upgraded hunting rifle.
Instead, to allow players the weapon they want, i would like to see skinnable weapons with a variety of modifications. That way, even though there is only one assault rifle, if you want to have an M16 (for example) you could modify it to be more accurate and lighter, but the tradeoff could be less damage and an increased chance of malfunction. However, if you wanted an AK47 you could modify it to be less accurate and heavier, but to do more damage and have a much lower chance of malfunction.