What's the difference? You're going to spend it anyways. And you'll end up spending more if you get it subsidized.
The smart people will buy the phone as a subsidized "upgrade" and then buy out their contract for $325. You end up saving $100 on the phone.
Because, I may or may not have $1000 available right now, but will overtime. Plus, I hold onto more of my money, versus spending it all at once. What happens if I needed $300 for a emergency car repair? Oh darn, I bought this phone off contract, so I could save $100.