I think people under estimate just how strong you need to get before you have the size where you look visibly muscular.
Take a look at Emeka from this forum, the man is stacked! And he's very strong to boot. Jslep is the same way, most others are too. Just having a basic level of strength will NOT look impressive unless you have a very low bodyfat.
Squats and deadlifts of around 300 just aren't going to lead to an impressive level if development, despite being stronger than most people in the gym. That really is just a reflection on the extremely poor standards in most gyms.