How does that make him one dimensional? He can score goals, is a strong playmaker and has a very strong transition game. If anything, he has a diverse offensive repertoire.
Because rightly or wrongly people see hockey players as three dimensions in this way:
1) Offensive game - which includes all of Bratt's strengths that you mentioned
2) Defensive/backchecking abilities
3) Physicality/intangibles (faceoffs and whatever else doesn't directly impact offense or defense)
You can say Bratt's offensive game is multi-dimensional certainly since he can score, pass and gain the zone pretty easily, but I could also see the argument for saying pretty much all his strengths impact only the offense (including puck entry and other stuff not directly being goals and assists). Right now the same is true of Jack btw...a great offensive player who doesn't add as much when he doesn't have the puck.
And obviously 1 and 2 mean more than #3, it's not like all three dimensions are equally important for individual players. And #1 means more for forwards than #2, whereas #2 means more for defensemen than #1.