Bravery in the face of massive threat despite being weak is more inline with his character goal of "brave warrior of the sea", being brave while being strong is like, cool... but would you be that if you wasn't strong?
His mentality is what's important to his character, rather than strength growth. Now as one of the commanders for Luffy, naturally strength will also be important, but blud is also only like 19 lol, if he progresses at a normal OP-pace of power growth, he'll be a monster in his 40s.