my observation has been that getting the first 90% of features/quality is pretty cheap and then as you start to try to close in on 100% features/quality for whatever your domain is the cost of improving software increases asymptotically somewhere short of 100% features/quality.

What people will pay for software seems to mostly depend of the costs of failure. 90% working software is almost always a better value prospect than 100% working software, unless your software failing means someone dies, or you place a trade that is off by $100 million.

In industries where the costs of failure are low (consumer, most internet, etc) the quality of software that the market will pay for is very low, and so the quality of the software being produced is very low.