I think the thing that bothers me most about the idea that this is a problem is essentially the issue of levelled loot, which was pretty much taken to its conclusion with Oblivion: as much as I loved Oblivion, it didn't take long before I needed to install an overhaul to make it worth playing, which did pretty much this: it gave you a chance of getting awesome items at a low level (as well as a lot of absolute tat at a high level).
The vendor in question isn't really all that easy to get to and there's already a built-in penalty in doing so in that all the magisters become hostile when you get to that point (or at least they did in my game when I tested it just now). It's always possible to exploit a game's advantages once you know they're there, but to attempt to then compensate for them being there is I think a huge mistake: there's too much of a risk of making the game either too bland or too awkward.
