Why should there be any benefit for donating?...
There shouldn't be in a perfect world filled with selfless people. BUT.... we aren't in a perfect world and there aren't alot of selfless people (and the few that exist are usually aren't in the best finances due to their own selflessness). I agree that donators should get perks that are "fun" and save "some" of their time. In fact, thats how they are now with illusion items, etc and enhanced houses. Now, "fun" and "some" can have arguable meanings especially to what perks they refer. You aren't going to make every single player happy with whatever the devs pick and quite frankly I'm sure the devs know intimately the balance of what donators should and shouldn't get. The normal players don't know and can only throw ideas out there for the devs to consider.
As far as buffbots go, I don't see how implimenting them into pocket plane would disrupt anything. Even if the buffbots require donations, allowing the players to even have the choice of saving time from the use of a buffbot is a plus as it is a choice that most players don't get.
Besides, most donators aren't college students or high school students with variable income at best (like myself). Those that do donate have a steadier income and have less time to spend in Dalaya. Making it easier and less time consuming for trivial tasks is a great incentive to donate.