> ... when it's so much more attractive to companies to rent their products to you for a constant stream of monthly income?
Which companies are you thinking of here? Amazon is still trying to drag book publishers into participating in this, and hasn't had much luck yet. Video subscriptions are more miss than hit. Spotify is the most mature, and (by your estimate) only has 60%-70% of what you want. And there's all kinds of complaints that Spotify doesn't result in the same kind of income that record sales did. I don't think the companies that own the products do like this model.
The reason they do it at all is because it's an effective way to compete with illegal downloading. The $10/month doesn't represent the actual value of the product (which for me at least is probably higher), but seems to represent about what the market will tolerate before it goes back to just torrenting stuff.
And that brings up a really good thing about these services: they address the market-efficiency losses of the copyright regime without needing to either break the law or change it.
For example, suppose the only way to get an ebook is to buy it, and each book costs $X. There are a small number of ebooks you value at more than $X, you buy those ones, and (in economic terms) positive value is created by each exchange.
But there is a much larger number of ebooks you value at more than $0 but less than $X. Those ones you would pay money for, and positive value would be created by that exchange, but the regime of "sell each ebook for $X" doesn't allow that value to be created.
Piracy fully reclaims that value, but has its own problems. All-you-can-eat monthly services also fully reclaim the value (as long as you can afford them and they allow the use you had in mind), but in a way that is mutually agreeable to everybody involved. That makes them a good thing to have around.
The real problem you're bringing up is that all-you-can-eat services don't allow some good and important uses, like saving stuff for later. But so far I'm not seeing any indication that they are replacing buy-it-and-own-it services -- or that content owners have any reason to want them to.