Clockwork at Out of Beta has an interesting post on questioning whether timers should reset based on the individual player's cooldown, or on a fixed schedule.
I think the general rule of thumb should be that if the timer can involve multiple people, it should reset based on a fixed schedule.
To see what I mean, imagine dailies had a personal cooldown of 22 hours. Anna logs in a 4pm and does here dailies. Betty logs in at 10pm and does her dailies. The next day they both log in at 6pm and want to do the dailies together. Only they can't, because Betty's dailies reset at 8pm. In these types of situations, fixed schedule resets are better.
In contrast, personal abilities generally work better when they are tied to the player.
The intriguing situation comes when personal abilities are tied to the group. For example, in-combat resurrection. These ability cooldowns started off tied to the player, but more and more they are shifting to be tied to the group. In WoW, abilities with a cooldown greater than 5 minutes reset when a raid encounter ends. In SWTOR, using an in-combat res puts a debuff on the group for 5 minutes, preventing more in-combat rezes.
It's an interesting shift in how cooldowns and timers are handled.