Originally Posted by
Nohara
I dont really care about older reputations on my alts, so there would be no reason to have them exalted at all, perhaps if you miss that one recipe or transmog item, it can be annoying to do all the rep again, but it is all just vanity. The newer factions our now rather easy to farm reputation with. You can either farm a few tokens from zandalari warbringers, or do to few days of dailies (with the commendations you unlock all valor gear litteraly in 3-5 days).
I feel if you really want something on a character, you have to work for it, it keeps the older content more alive. I am no fan of keeping everything equal.
The only reps I can think of that would be better of shared, are the PvP reputations. You PvP for your faction, not your character.