I guess it could be nice if they added a rare mount or something to the drops on T5. Maybe add an item similar to Mirror of the Whorl that you can upgrade your Allagan weapons with too (Now with added glow!).

But I think that even if they did increase the rewards for T5, it wouldn't solve your problem OP, as most experienced players that want those items will stick with their experienced groups to farm it, rather than joining newbies.