As a costumer, a rather pay more for a plugin that I know will have long lasting support (as Spriter, or a lot of tools on the Unity Asset Store), than pay 5 bucks for a simple plugin that will not be long supported. I think that the freedom to set their own prices is better for the seller and for the buyer.
Plugins and tools add much more value than assets, because they offer a change in workflow and on the toolset at your disposal. I bought some beefy priced editor plugins on the Unity asset store, but I feel like they added value to the software, and that way, the creators see like the time investment is worth it and they can keep make high quality addons.
I am looking forward for the time when the store is full of amazing workflow tools and resources, the graphical assets and such are ok, but I won`t use them.
Anyway, just my 2 cents. And sorry for my "engrish", it is not my mother language.