I don't mind having ads while listening to plain radio. But on Spotify there were more ads than songs lately, so they forced me to buy a subscription. They did not reinvent the radio, they made it worse.
So are limited free demos a shitty method because you then have to pay to get the full experience? I don't understand why people are so upset that the free experience gets worse, economically it makes sense and any company would do it. They do not need to offer a free service at all, but they do it to help cultivate a premium user base. It's pretty consumer friendly they offer a free version to let you make sure you want to use Spotify before you pay. I just don't think offering a free product to entice paying for the full thing is a "shitty method".
Offering the free tier is not the shitty method, using ads is also not the issue as such...it's the overloading it with incessant advertising and basically auditory harassment to coerse you in to buying premium that is the shitty method.
I'd agree that's annoying yes, but it's free. There comes a point where the amount of free users upgrading to premium isn't enough, so they're left with either changing the free service to boost that number or remove free as it likely loses them money. I'd agree that it's shitty yea, but the free product is meant to be a preview to entice premium subscriptions. If they aren't getting enough upgrades, something has to change (in their view)
Is that weird somehow? You like a thing. Then the thing changes into something worse but there is a paid version of the thing which is still good. You decide whether you liked the thing enough to spend x amount of money on it.