Interesting.
Would most people be happy half-assing a job, getting $60+ million for it, getting fired (and probably getting a huge severance package) and living it up for the rest of their lives? Probably. At the same time, most people would also want to move up in their careers, make an impact, do a good job and be rewarded for performing well.
The actual amount of money may seem irrelevant in that, in terms of buying power, it's all about the same whether you're making $10 million a year or $20 million a year. Where it still matters, though, is valuing yourself professionally, and determining how your employer values you. There is something -- I think not nearly as much as executives and corporations would argue, but something -- to be said for the retention aspect of these high compensation packages. If every company lowered their executive comp packages by 50%, the world would probably be better for it and the executives' lives wouldn't change that much. However, you have to pay for top talent or some other company will.
As others have mentioned, a lot of the grandeur of this grant is due to her being recruited away from the top position at another successful retail company. If you want to lure someone away, you have to give them a reason, and you also have to make the person whole on what they're walking away from by leaving their previous employer.
I think when you get to that level, it's all about remaining relevant, and remaining in the "club." You want to perform well to get your compensation so that you can tell all the other execs you hang out with that you did it. You have self respect and dignity, and a drive and passion for your work that won't be satisfied by taking your millions and moving to an island.