My 2c is that it's not only your customers that you need to keep happy, but also your own employees. Engineers look for projects that don't give them headaches

My 2c is that it's not only your customers that you need to keep happy, but also your own employees. Engineers look for projects that don't give them headaches while working on them, and those that help them learn the right things. At the same time, they do look for maintainable and extensible codebases that they can enjoy working on. The problem with bad code that is a clustermess is that things leak everywhere, and fixing one bug will lead to another. You won't have a product that is stable for your users either. At one point your engineers will make a point of rewriting things from scratch, but management may stop them. This will force them to quit ultimately so you'll have to deal with loss of resources. On the other hand, using your users for QA is terrible. They do not report bugs at all, they get frustrated and spread the bad word. If they're paying users they will start looking for alternatives at one point. This is all a part of your business.