There's a difference between allowing customization by the user (good) and by the manufacturer/carrier (bad). Users will pick apps they like, by definition. Vendors will pick apps just to be different. That's sort of OK if the choice is really better (e.g. bundling Swype on my Epic). But they get it wrong more often than not.

Example: samsung wrote their own camera app. For reasons that are clear only to them, it refuses to work (literally, it pops up a message box and exits) if the battery charge is less than 15%. I'm sure they thought they were "conserving" battery (because clearly they know better than me how I want to spend my battery energy). But of course the real effect is that this is a $250 phone that won't take pictures in the evening. And this is routine in the market, Samsung is hardly the only offender. That's the disaster Google is hoping to avoid.