First off, I dont see a wisp as an economical problem, only 60g's for one, and for that 60g's you can take out maybe 3-5 skellies and possibly some mana, leaving your oppoenent no exp. and if the UD DOES manage to coil/nova your wisps then you still did a job of wasting their mana and thus diverting their nuking cababilities for a coouple of seconds.
i see your point with abolish magic, but a priest has about 400 mana? and abolish is like 70 mana. early game you have to constantly heal your units and 70 mana is a shit load of mana to be used- chances are your priest wont have enough mana by that time. also, priests can get its ass whooped by 2 hunts in about 4 seconds.
and dragons are still a problem, they make you micro more while killing off anything that uses mana. if you micro your necros to the point where they are away from the battle then the NE player has done its job of seperating your army which makes it an easier win for them.
i forgot to mention that nova can't take out a couple of wisps, maybe just one. and I never really seen an NE player yet group his wisps together, theyre usually spread out on the trees and he uses them 1 by 1 when he needs to. and if your lich has level 3 nova, then that would mean that the NE player didnt do a good job of harrassing you which ='s a gg to the NE because UD late game is tough for most races.