I asked this question on a trucking forum and the general consensus was that it would make backing up much harder. Does it eliminate any sort of blind spots?
According to the Tesla site about the truck, the reason for the center mount steering wheel is:
Enhanced Autopilot helps avoid collisions, a centered driver position provides maximum visibility and control, and a low center of gravity offers rollover protection.
If you look at the (what I take to be an artist's rendition) of the cab of the truck looking out, you can see there isn't much room for it to be anything but a center placed steering wheel:
The cab of the truck is quite narrow, which provides for better aerodynamics. These trucks (as far as I know) aren't made for long distance hauling, so most likely wouldn't have the availability of a sleeper or other things which conventional semi-trucks have need of.
With having visibility the same on both sides, it seems to me it would make it easier for backing the truck up. To me, the talk you are hearing elsewhere is just talk because truck drivers of conventional trucks are just "used to" how things are not equal in the side view mirrors. If they used this truck, they'd get used to the new paradigm very quickly whether they believe it or not. (Full Disclosure: Both my Dad and Father-in-Law were both truck drivers. I've done some driving myself.)