I wouldn't want any company to buy something just because they have the money to do it. If PRU doesn't think that the metrics are worth the investment, and they have cash to spend, just like any other company that buys back stock they think it's a better return on investment than anything else available.
As a shareholder I'd rather see higher dividends though.
FWIW, CS rates MET as outperform also with a PT of $68.
Flip a coin.