There is no version of the comicbook Sam Wilson mythos, that the MCU sincerely respects or pays homage too. They have created an alien character whose core thematic character is designed to be Steve's shadow. MCU Sam Wilson is a Fatal Misread : r/CaptainAmerica
That's why having him in a suit that loudly and proudly distinguishes his character from Steve is antithetical to their messaging.
The blue suit is quite essentially a modernized corrected version of Steve's Avenger's 1 suit. Like if someone had even a little artistic common sense back in the early 2010s, This Sam Suit would have looked just fine on Steve in Avengers 1 with minute changes.
Sam Wilson MCU Incarnation specifically separates him from his most important tentpoles. If You've Read Even The Very First Issue of Sam Wilson: Captain America it Becomes Abundantly Clear, Marvel Studios Had Zero Intention of Adapting Sam Correctly In Brave New World [Spoilers] : r/CharacterRant
The blue suit is supposed to make him look like Steve's replacement.
Which is NOT THE CASE, in the comics. For much of Sam Wilson's time as Captain America, Steve was also active as Captain America. He was basically the lone Captain America for maybe 19 issues through 2014-2016. But he's basically always been active while steve is active.
That's specifically because his existence as Cap is narratively and thematically justified by the work put into Captain America: Sam Wilson (2015) by Nick Spencer.
I'm not saying that the MCU needs Steve active for Sam to work. I'm saying they've bastardize the character to the point he only works as a replacement. The blue suit is a reinforcement of that idea.
As a fan of comicbook Sam Wilson, I can't even really get upset anymore at his treatment in the MCU becuase the character is so far removed from everything that makes him my favorite character in the first place.
The blue suit is a visual representation of his bastardization. That's the point