If I find a product useful and a 1-year subscription is available and doesn't feel expensive I will subscribe, then cancel renewal on it. This forces me to reevaluate if it is worth it every year.
That's a nice theory but a lot of subscriptions are decidedly not cheap on an annual basis ($100+) and there's a lot of potential for money leaks you aren't pro-active about. Though I actually agree that subscriptions as a principle often align developer and user interests.
There has to be a lot of value in it for me to pay that kind of money for temporary usage of software. The closest thing right now is Jetbrains all products pack. I consider every November when the renewal comes up if I am going to continue. Adobe Photographers subscription is a great deal because the total cost for a year is way less than the price it used to cost to buy Photoshop flat out.
Adobe Photographers is actually a pretty reasonable subscription for me. I don't use Photoshop a lot. But I do use it and Lightroom I would do pretty much every upgrade anyway. If I just did the occasional Photoshop thing, I'd probably buy Photoshop Elements (Or use GIMP).