Dont underrate MP. They are not that much useful when taking controlled composition and such, but when you take a concert picture or something where you do not have full control over situation, then more MP means more cropping withe acceptable results.
Thats the most significant advantage of more MP.
however when you increase MP without improving the actual image quality, you still cant crop it any more than you could before. IMO the E30's and E620s 12MP is no advantage over the older 10MP sensor. In fact, I think its worse at ISOs 800 and above.