I agree. Its like the best infomercial product...
"Try now for 120 days, if you don't like it just throw it away" except for the fact that you probably accumulated a lot of docs/pics/videos/apps/etc by then and now you are at a point where you should probably buy it. And the average home user will think they will lose everything the have on there if they don't buy and activate it.
I think it was a smart move, not just to let someone have a "free" OS for 120 days, but giving them a test drive. If that person chooses to use it as their main OS for those 120 days, they are most likely going to buy it. PLUS the average user doesn't know how to rearm. They are gonna try/buy after the 30 days.
That's what a friend of mine did with Windows Home Server. He got the trial, after 30 days of it backing up 5 of his machines, he bought it because he was already "knee deep" in all of of his backups, and everything was running perfect.