Why are rechargeable batteries not more commonly used?

I recently purchased a set of Sanyo Eneloop rechargeable batteries and I’m really geeked out (I’m not sure what it says about me that I’m this excited about rechargeable batteries).

I just received them and haven’t used them yet, so maybe I’m missing something, but I just don’t understand why everyone doesn’t use rechargeable batteries. It seems like a no-brainer. The Eneloop last for a really long time, they supposedly cost only 4 cents to charge, and re-using batteries will cut down on waste. Why wouldn’t everyone use them?

I realize you plunk down more money in the beginning, but they will eventually pay for themselves, plus no hassle of running out and having to go to the store. For $30, I got a charger, 4 AAA, and 8 AA batteries. Sanyo claims one battery is worth 1500 disposable batteries. Even if that’s not the case, 20 AA batteries cost roughly $10 at Target. So, these batteries should ultimately pay for themselves in not having to buy disposables!

Why aren’t they more popular?