When ATC installed my Bobcat, they left the tailgate on and at first I was bummed that they did, but after the first 5 minutes of using it I was so glad they did. It's a very sturdy step up to (or down from) the camper without having to totally rely on whatever little step stool you're using. Plus, if you plan to store things on top of your camper (kayak, roof rack, etc.) you can easily stand on the tailgate and fully access the roof from side to side without having to constantly move a little step stool around.
The "porch" is also a very handy place to set things while you're in camp or to stage things you're packing/unpacking from the camper.
The only drawback that I can even think of is that I may have to get a receiver hitch extension if I want to use my Thule bike rack. As it is, I can easily hook up my small utility trailer without an extension, but extensions are only like $10.00 at Harbor Freight, so it's not a deal breaker.
Plus, my porch is deep enough to hold a Jerry can of extra fuel or water on each side of the door (something I'm considering making a mount for). For me, the benefits of having it on far outweigh having it off. In the end though, it's personal preference. I see more rigs with the tailgate off than on, but that doesn't mean they ever tried it with the gate on. Either way, it's easy enough to take on/off once you get your rig.
Good luck...