Progression achievements are fine, but I said games that -only- have those achievements are doing it wrong. Personally, I would tier it like this: 500 points for a normal playthrough, 200 for higher difficulties, 100 for random stuff (like Crackdown or Dead Rising), and 200 for challenging achievements. But obviously it depends on the game... it's not like you can have some skill-based achievements in a visual novel or something.