Why not??

because it is hard to do, as there are many types of references which may build a complex graph for a reasonnable assembly. Moreover, a deep knowledge of SW rebuild process is required. So the real question is : are you really prepared to pay hundreds of $ for a tool that detects circular references ? One "simple" way would be to add circular references detection in SolidWorks rebuild algorithm itself : before rebuilding, clear a flag on all references. While rebuilding, set the flag when a reference is used, but if the flag was already set, then it belongs to a reference loop. I'd say circular reference handling is SW business, not a partner's.

Of course it is a SW issue. That doesn't really change the fact that it should be done. And it should have the ability to indicate where the circular reference is. I, for one, would be quite willing to pay extra for that. Accidentally creating a circular reference, and then either spending the time to find and fix it, or paying the performance penalty for having it costs a lot of money. Definitely more than a couple of hundred $$ per year.

Oh, and BTW, this can be done. UG has had it for years. Which leads me to wonder if it's already in the parasolid kernel and SW just isn't using it.

Since I've already blown the nda all to tatters, check out this blog post:

If and when. I really hope that they do make it into the final product. This is the kind of update that is worth the time and effort to make happen. Not just eye candy like so many 'improvements'.