I wonder what made Amazon go with this course of action. Plenty of the other providers have done basically the same thing: the previous price now includes ads

I wonder what made Amazon go with this course of action. Plenty of the other providers have done basically the same thing: the previous price now includes ads and you have to pay more to stay ad-free... but they've all done it by raising prices and introducing a lower with-ads tier. To me it feels worse to have your service downgraded with the option to pay more to get it back than it does to have your price increased with the option to drop to a worse tier. That's sort of irrational, as the price increase is basically "opting you in" to pay more, but also just reflects how much ads suck. In terms of Amazon's choice, my best guess is that it's a reaction to an effect I've seen other providers describe: the ads are so lucrative they actually earn more on the lower-tier customers.