Have you ever done a TR2? Why do you think it needs to be longer? What is the challenge in killing swarms of Ogres/Giants/Trolls etc with some sort of "+3 Flaming X of PG" vs. a LitII? It's the same challenge, just that using a random weapon takes longer. All you're doing is increasing the grind, and not by much TBH because mobs have low HP compared to the damage output of a pack of power-leveling TRs.
Epic weapons are different. They are ML20 simply because they are epic. There are many epic weapons that could me lowered to ML10 and no one would notice because they're ****.
Must leave due to time.