As a paying customer I am glad that Heroku is cutting down on the free usage. They are using AWS so free usage means actual expenses. Sure, it can be seen as a marketing expense but Heroku is well known now and don't really need it to gain awareness.
I am happy to pay for my production, but I feel as though part of the benefit is that I get a cost-free development playground. If they take away that, I'd rather put the money into something else where I get even more control.
I guess they want to go leaner, which is fair enough, but they will lose paying customers as well.
For a cost-free development playground, they have the hobby tier. You can run your dev apps for 350 hours per month - that's a lot of dev testing time.