Would it make sense to have a bathroom without a sink?
Unless every one of your guests wipes the inside door knob down (and disposes of the cleaning material) each time, you have no guarantee of hygiene, assuming you do the same thing. Each time.

And, it's a kitchen. We humans have evolved to that point where we generally don't allow (or try not to allow) fecal bacteria to commingle with the stuff that we eat.

What if you need to clean up a little kid who's not quite potty trained? Would you go back and forth between sink and toilet? How about vomit in the bathroom? How would you clean that up without needing to rush back and forth? So many other use cases come to mind.

Yeah, I wouldn't recommend this.