I would not fly if I had to get a random seat on check in. My luck it'll be right next to the toilet.
I will add the cost of the seat reservation to my bottom line when selecting an airline. If another is cheaper and I can select my seat, I will take that one.
Why is it airlines today only 'listen to their customers feedback to improve service' when it makes the benefit less for the customer, the price more to the customer, or both?