In Novell's case I think its inertia. There was a time that Novell offered a suit of solutions that worked together well and made things easier. Eventually, industry surpassed Novell.
Good IT managers are conservative. In the short term, "If it ain't broke don't fix it" is a good motto. But sometimes sticking with the old becomes a burden and its good to be proactive. Knowing when to migrate or upgrade (and when not to) is what separates the good managers from the great ones.
I'm guessing you are an engineer. The willies you get from sales is your BS detector going off. The sales people are selling product they don't completely understand. The management making the buy decision is buying a product they don't completely understand. But the sales people and the management speak the same language. The engineers usually do not. So the management trusts the sales people and the "monster" is purchased.