Agree with the OP. Daily allowances should stack and accumulate up to at least a week if they haven't been "used". The only other modern MMO I play frequently, Rift, also does this with the Dungeon bonuses; they stack up to 7 (a week).

What this would allow is for those with jobs and families who can only play on weekends, usually for more extended periods, to be able to "make-up" for the weekdays when they can't play.

+1 in agreement OP.