Two points:

1) The games industry does not have a revenue sharing agreement with game rental companies like Hollywood does with the movie industry. There is zero financial motivation to support rentals or the used game market.

2) If you're just renting a game what difference does it make that you wouldn't get the "value added" features. If you're going to just be playing a game for a short while does it really matter if you don't have some multiplayer maps in a shooter or songs in Rock Band?

Since people like their analogies, imagine that the game you purchased is like buying an appliance. And let's say that appliance comes with a warranty. You're more than free to sell that appliance to someone else, but if you expect the company to honor the warranty on the product when it's resold, you're crazy. The second-hand buyer gave nothing to the company that made the appliance, so why should the company pay for anything at that point? It's the same way with these features that games are adding.

I do agree that if the companies are going to do this they should at least provide a pay version after the fact, especially if it's multiplayer-oriented content.