Constitutional law is quite arcane and complex.
Only ignorant people look at it and say "It's easy."
Scalia is probably the brightest intellect on the SCOTUS. Go read some of his decisions, especially the "easy" calls. Keep in mind that it is not enough to come to a conclusion. A conservative justice like Scalia must also contend against the gloss placed on the Constitution by extremely skilled liberals who are determined to manipulate the text to do their bidding. It isn't enough to say they're wrong. It must be shown through skillful analysis of the facts against precedent (sometimes more than 200 years of precedent) WHY they're wrong. That takes a first-class intellect and more.
It is difficult enough to articulate a coherent opinion in a First Amendment case. Try articulating an opinion on an anti-trust case or one involving the applicability of provisions of ERISA or a trade agreement.
Skill as a managing partner of a law firm does not translate into skill as a jurist who is expected to circulate an opinion that gets the approval of four other justices.
And this accomplished woman is the village idiot?!?