Actually this was my graetest gripe with the Legacy system as well. Being time poor and only having recently levelled a character far enough to unlock my Legacy I was bitterly dissapointed with the fact that the legacy names (current only method of getting a Surname) was unique restricted and inflexible.
Of course reaching this level this late post release meant that all of the Legacy names I would want have been taken, and this also means that all of the 'quirky' Surname interactions I desired for my characters are unattainable.
It would be great if BW offered a Surname service ingame that was seperate from the current Legacy system - it would be great to be able to name my characters the way I initially intended. I understand the need for unique first names for characters, but surely we could have non-unique Surnames... please, please, please!
As for the other elements of the Legacy system, I quite like the sound of what is proposed and I have no issues with things being retrospectively fitted - at least BW have something in place to track and reward those who are fortunate enough to have time to play to end-game and beyond.