Why do all your alts need faction gear again?
You can get into LFR just by doing heroics...
compare a 476 lfr piece with a 489 rep piece.
Consider that you only need heroic dungeon gear (463) to do NORMAL raids and get equivalent or better gear.
As you can tell I like achievements, as soon as I hit exalted with a faction from doing dailies I stopped doing them.
With account-wide mounts/achievements there is almost no incentive to continue doing dailies on alts as it gains you marginal gear benefits that you don't actually need to complete normal raid instances.
The only legit gripe with rep grinds is when you have profession recipes on the rep vendors that you cannot obtain on your alt with the required profession. If they allowed you to buy these if you had a main with the rep (or have the grand commendation applied to the account) I see absolutely no issue with reps and alts.