Are there really stockholders that don't want expansion in the parks? What are they stupid or something? :shrug:
No - they are investors, not fanboys like us.
Expansion ain't free, and money used for that isn't used for other things. Stockholders will want the cash to spent in whatever way they think will generate the biggest return. Some would think park expansion would do it -- others would probably think the movie business is the way to allocate resources -- and others would be in favor of buying back stock.
The stock buy-back is actually the easiest to analyze. Let's say you believe that Disney's stock price today is 20% below where it should be because Disney's share price has been driven down by concerns that the economy will hurt Disney far worse than you believe it actually will hurt Disney. You'd probably want Disney to put any available cash into buying its shares back at today's market price, because you would think there's a built-in gain of 20% -- a level of return that it virtually impossible to achieve through other investments.