Changing your trany at such interval is nice way to keep you car well maintained.
Your trany fluid should be at an optimal operating temperature. If the trany fluid is below or above its optimal temperature then less protection is provided. This is why, it is always a good thing to let you car warm up before you stomp on the LT1’s or your SVT Cobra on the freeways.
Sometimes when driven hard for long periods of time (on a track course) you trany fluid will overheat and not provide protection (just like your engine oil). Your car has a factory trany oil cooler already. But an additional one will provide extra cooling to keep it within “optimal operating temperature”.
The $16 fitting is only 1 of 4 that was used, plus the steal braded lines, the oil cooler its self, and brackets came just a little below $300. Not including self-labor.