As long as XP is reduced for enemy groups not designed for 50, I don’t care either way.
For example, a Hellion minion is probably about as dangerous to a level 50 as an underling tier foe from a harder group. The XP should be dramatically reduced to account for that.
Basically as long as the XP is complete trash for trash mobs, do what you want. If you want to get good XP for trash mobs, however, then I can refer you to the latest /jranger gif.
Drop rates would probably have to be reduced too. Maybe merit rewards as well. This would throw off the risk/reward balance a lot so you’d have to mitigate basically all kinds of rewards.
OP’s awkward insistence that he is about to drown in a deluge of hatemail and flames gives this post a weird vibe, on another note. Gives you the sneaking suspicion he thinks disagreement constitutes hate or flaming.