Generally speaking, only new people will need/want all the exp from Aurum Vale - people levelling a second class, for the most part, will only do the first room of AV for exp.
New people won't know that you get bonus exp from the fruit if you let them spawn into mobs.
Unless you have a full party of newbies, you'll get synced 50s desperate to get out of that horrible dungeon as fast as possible, which means not letting the fruit spawn morbols. Basically, it's pointless to expect people to want to get full exp there and to know how to do it even if they need it. Also, a surprising number of people just don't read the chat, even approaching level 50 =/ So asking doesn't always work either.
Regardless, you really shouldn't punish yourself by running AV over and over =P I groan internally whenever it comes up in roulette, it's 100% the worst dungeon in the game to pug xD