I like having point to be honest. Lets you budget, look for deals, trade games for live point at EB games etc...
Also it keeps you from buying things that you don't want to buy. For example, while I had a PS3 I went in to a PSN store and looked at Fatal Inertia game for download. I wanted to see how much it was. Then by mistake I pushed the confirm button instead of back and bought the game as it charged my credit card for the game.
With points that could obviously happen if you have lots of points but if you keep your balance low and you add pts every time when you buy something, it wont.