I would 100% back this. Unless a smelted item is collected after smelting, the Hopper is kind of useless. If I have to manually remove an item, I'm at the machine anyway, so I may as well manually load it while I'm there. So in that respect, a Hopper should work both ways by sucking items out as well as loading them automatically.
Alternatively, have items stack in a machine if loaded by a Hopper, so when you collect manually you're collecting multiple items, not just one at a time.
I'd also want the Hopper to work on all four sides, so one Hopper services any adjacent machine, not just the one in front of it.