The red underwear would look out of place if they tried to bring it back now. Best to move forward. If I had to make a change, I'd put in an S shield that wasn't textured. I don't know why the S had to be textured.
The textured, rubberized look is pretty much a staple of every superhero movie costume nowadays, and I doubt it's going away.
As for why they texturized the one in MOS, it was probably because the S was so freakin huge
that they had to do something.
If there's any change I would be okay with, it's lightening up the blue a little. The midnight blue of the first movie was so dark it almost appeared black in some shots of MOS.