Opinions are like assholes, every body has one. As art critics (in fact, all critics) are only heard when expressing their opinions, it kind of stands to reason that the reaction stinks.
Having said that, the majority of artists who today are considered the real greats, responsible for some of the finest art works in history, were either completely unappreciated during their lifetime and died penniless and destitute, or they were appreciated for things other than their artwork and derived income from sources other than their artistic endeavours.
Granted, George Lucas is never going to die penniless (but if he wants to give me all his money 5 minutes before he dies, just to prove me wrong, I am not going to complain), so he does not fall into the penniless category. Equally, he is not appreciated for anything he has done outside of the Star Wars franchise, unless you count the setting up of Industrial Light & Magic and similar business ventures, so he can hardly fall into the "artistic genius who earned money in other ways, with his artistic genius only being appreciated after his death" category, even allowing for the fact that he is not dead.
Personally, I can come up with a list of potential "Best artist of our generation" candidates that is longer than the credits for all 3 Star Wars prequels put together and which would not contain the name "George Lucas", but that is going to be my opinion, which is no more valid than Ms Paglia's effort.