Of course the company that treats its software products is still profitable, so there's no motivation or reason to change anything. Add a few features quick and "cheap" which sells a few more units and continues cruising on.
Very few companies are concerned with software maintainability. Yes, it saves money long run, but the types of people that tend to end up running companies that make software are short sited business types that are concerned about turning as big a profit as they can the next quart to year (exec bonuses are at stake!). In reality doing things "right" will mean less cost the entire life of the product. Yes, initial profits will be delayed, but over the life profits will be higher due to lower maintenance costs (and maintenance is the majority of a software's life cycle).
Your example is a little different as it sounds as though it was on the right track initially, but someone up top push some quick new features. Which works for the first while, but then coupling starts making any additions down the road hell. Of course they pay the price to do those additions (poorly) because rework costs even more than a feature that takes 50-100% longer than it should to implement. And it gets worse and worse, and eventually the product is dropped because it costs too much to do anything to or you've burned too much customer good will with your buggy POS. But hey, it was a good run and they made profit and got bonuses and have this shiny new product to drive into the ground.