It is probably without good cause, but I don't like any kind of block or restriction in a transmission cooling line. I'm just a stubborn old man that likes simple stuff.

To me, any kind of restriction or block is just another thing that can fail. Several years ago Mopar put a flow blocking check ball in the cooler line that would stop the converter drain back. That little check ball in the one cooler line was responsible for more transmission failures then the converter drain back ever caused. In pretty short order, the check ball would "collect" enough stuff from the fluid flowing through it that it would stop the fluid flow through the trans cooler and cook the transmissions.

When I took my 96 Dakota with 44,000 miles on it cooler line apart, the passage was almost plugged solid, I have removed the check ball and the hose section it was in..I have no problem starting the truck and putting the trans in neutral for 30 seconds before I put it into gear to move on that first drive of the day.

If running the trans fluid through the radiator trans cooler solves the cold weather shift problem, I'm running the fluid through the trans cooler in the radiator. I like simple solutions.