What inconvenience to residents? South of I-155, it's almost entirely a new terrain routing over farmland. Even the section between north Memphis and Millington avoids significant development. Besides which, as mentioned above, a bypass of US 51 from Memphis north to at least Covington is already needed; recently-widened TN 14 relieves some traffic but really only helps with the section from Millington through Atoka.
I guess it would be less of an inconvenience to the residents and more of the fact that my proposal would greatly reduce the number of new miles needed to be constructed (instead putting them onto existing freeway). Furthermore with the new bridge people could bypass Memphis, even if still wanting to go on I-55 (I-69 to I-269 back to I-55)
As for the traffic issue, they can easily extend the beltway around, back to I-55/69 in Arkansas, and if they really want the routing of I-69, they can always complete the road and name it something like I-340.
I just believe that the proposed I-69 between Dyersburg and Memphis is just simply Too Close To I-55 to be of national use.