I wouldn't consider a stock repurchase "wasted" money.

Management has incentives to improve shareholder value (as mentioned above, they are usually shareholders, after all). Often times management will justify a stock repurchase by asserting their the best investment opportunity at the moment is the company itself. That is essentially what the company is doing: investing in itself.

A stock repurchase could improve the stock price by decreasing the supply of common stock on the market. In addition, the balance sheet is affected: assets are decreased (due to a decrease in cash) and equity is decreased (due to a decrease in outstanding shares). Generally speaking, this means a balance sheet analysis will show improvements for Return on Cash and Return on Equity. This may be viewed as an indication of improving financial strength in the eyes of investors, creditors,and analysts.