trans oil cooler line size?

[oldsmobile joe]

so my question pertains to the steel lines that run between the trans and oil cooler. our cars came with 5/16" lines and are attached with brass adapters that have a 1/4" opening.
newer gm vehicles, 94-96 caprice for example, have 3/8" cooler lines, but are still attached with brass adapters that have a 1/4" opening.
so what are the advantages of a larger, higher flowing cooler line if they still go through the same 1/4" opening at the trans? i feel like I'm missing something, this doesn't seem logical.

 

[Tony1968]

Yes that doesn't make sense. But I'm sure you can change the fitting at the trans to allow the larger size all the way to your cooler. for instance I have 6an fittings on trans and same lines which are 3/8 of an inch