Basically I think dispensers should place blocks instead of throwing the entities. This would make concrete making easier (though it's already easy). New door designs would be possible with ability to store the door blocks(likely sand, concrete, anvils) in chests.
If you don't like the feature, it wouldn't hurt most current designs since we still have droppers.
What do you think, should this idea be added, expanded upon, limited to certain blocks or just not a good idea at all?
I've made a command block version of this idea before in 1.12(not sure if it works in 1.13+) that works with sand, gravel and anvils. I'll be happy to upload it if anyone wants to tinker with it later.