DOORS is a high-quality, high-end system-requirements development tool. Its primary failing is that Rational made the cost of the product and learning to use the product so expensive that very few people or companies were willing to absorb that overhead without a guarantee of revenue to compensate for it.
The problem with the product is that customers, usually government agencies, would demand DOORS experience when no-one in the market had that experience. The result was that government contracts got delayed for years because of this circular problem.
Oracle made the same mistake and that is why SQL server exists today. Other companies have made similar management mistakes.
A second problem with DOORS and similar products is that customers and new IT managers (under 45) do not understand the discipline required to make effective use of these products and often put meeting a deadline before quality. This results in poor and inefficient design, and unmaintainable systems.
The University of Waterloo Maths faculty had the relationships with software and hardware manufacturers in place, back in the 80's, and this gave us graduates a huge advantage when entering the work force.
My opinion after 25 years in the industry is that companies that manufacture software development tools should make learning to use those tools as cheap and easy as possible so that software developers can use those tools and thus recommend them.
My advice to organizations tendering bids for software systems is to make sure there are people out there who can use the development tools before releasing the bid for tender. The bid review process should require the bidding management team to demonstrate with examples its competence in the use of configuration management, quality assurance, requirements reviews, design reviews, and code inspections. If the bid response does not have these activities scheduled with a real person assigned its not getting done.