I believe that a rebalance as your suggesting would potentially have a greater negative affect on New Players, either Old Players Returning and starting from scratch or True New Players. Now having said the above I am some what unclear what above question -> Issue -> Suggestion really is all about. As the power of the Template has increased, so has the power of new / introduced MoB's as far as I can tell. So I guess the Questioner may be suggesting they would like to fight a Reaper and get a Real Challenge while at Magery 120, Meditation 120, EvalInt at 120? Also I am fairly certain that some MoB's are now involved in lower level quest. Spell Weaving comes to mind and Killing Reapers is on one of the Quest Chains. I would feel fairly shaky about toughening them up unless it is going to be a given that to complete the task the character may be required to kill 20(?) level 120 Mobs. I will think on this and if I can come up with a pro, other than nostalgia, I will edit this post.