Yah often that sucks.
But it gets a bit better at higher levels.
I can say I was killed by someone 5 levels below me and today I fought a few times against someone 5 levels above me. Every time I finished him easily with ~50% of my HP left-
225 EXp wohoo
(or maybe more?)
Maybe the range should be decreased at lower levels (there are mostly enough players online anyway)