Adrian, I think you have a valid point. But the companies that you named are just support companies and that has a different financial model than companies that profit from IP. You have to make a choice between making money via the support mode or the IP mode. If you choose the IP mode, then you do take on the task of maintaining software - but just the part that is proprietary. I, personally, do not want to be in the support mode; it is too much work.
-Al
