The problem is that new features and improvements are not forthcoming, and when software is closed source it is impossible to take business elsewhere if the copyright holder loses interest.
When you buy software, you expect it to improve over time. Name a mac developer who posts on their site "we're no longer updating this software, but please buy it anyways". It would never get a single sale.
I don't mind paying for upgrades. But I want these upgrades to exist, and for the developers to commit to the product they are selling and improve it over time.
When you buy a license for the software, you are buying the license as of this date. You should not ever buy software for future possible improvements. The only situation in which I'd say it is really necessary is OS security updates.
If any customer ever asks me: "I'll buy it if you add this feature", I always reply: "please buy it based on current features otherwise I cannot promise anything".
You're living in a fantasy world. It may be how you think the software business should work, but it's not how it works.
Your opinion as a software developer means nothing in this case. Ask your customers what they think. You might be able to get away with this strategy for a little while, but it's a surefire way to kill any product. Stop updating an app for a few years and see how great your sales are after that.
