Normally i would agree on asking some kind of compensation, for sudden changes. This however is not a "sudden change"... this is due to a bug that allowed old chars to keep skills that would been deleted, upon change to upgraded skills. Of course you could always chosen to not upgradde and keep the old skill. Don't think anyone refused the new upgraded skill, just to +20 the old one. Considering you really benefit from having the old skill for so long, out of place to ask for compensation, when you shouldn't had it in the first place