I guess one worry is that the current iApps/ iProducts would loose their strength- and be seen as old; consumers (and professionals for that matter) can be fickle, ie: "You are only using the iSight?- We have jSights here",
or "The iPod is old- if you look at the rest of the Apple range, they are now onto j prefixing, so don't buy an iPod now, wait for the jPod- they are going to announce it soon enough, and it goes to 11"

But I agree, a change is good (if the change is for the better).