Tunica has less than 1k residents, is that really worth control city status? Also, why not route 22 up 269, then throw it onto 385? then there's no need to upgrade 78.
Despite Tunica's lack of permanent residents, it's a popular tourist destination; therefore it has earned control city status.
And I suppose routing 22 up 269 to 385 is definitely not out of the realm of possibility. But it would still be a 2di ending at a 3di, but a different one than before. I think Germantown or Collierville could care less if they are served by a 2di, and they might appreciate the long haul traffic NOT being routed along 385.
Anyway, Lamar Ave is essentially a destination for a lot of the truck traffic in the area. Memphis is known as "America's Distribution Center", and many of these disto centers are located along Lamar, which is not far from the airport and FedEx. As for the regular auto traffic, many of those folks may very well end up taking 269 to 385, especially if their smartphone-based mappng apps detect backups on Lamar.
The main outcome from all of this is that 269 gives Greater Memphis more options, which is a lot more than can be said of other major metro areas, namely the one at the other end of I-22, and an even bigger one further east.