Hmm... I can see the points of views offered. I can see both sides as I sit here thinking about it. The down-scaling keeps a level of challenge which often disappears from games like FF and Skyrim (or any game with levels and level locked zones). It prevents certain levels of boredom. That actually could be a very interesting point in the games favor for me.
On the other hand, it is still nice to be able to "steamroll" in favor of a friend, at times. That was one of the greatest things about Guild Wars. If I, or my friends, couldn't have ran each other or simply just rolled through lower level zones, it would not have been entirely possible to play with my friends. I, for one, don't have as much time to play as most other people. Thus I tend to be behind the curve. This problem isn't really fixed by down-scaling simply because not everyone enjoys going back to a zone they've been in (its boring because they have experienced it already). They are far more likely to come back and help if they can just destroy enemies quickly and move a friend along past it.
What is this side-kick system being referred too?