Looking at the 04s... which are 17 right now...
Who are the best forwards in that draft?
Verreault, Côté, Dumais, Oliver, Vidicek, Woodworth, Savoie, Swan, Mathieu, Fontaine... I guess you see where I'm going with this. All between 5'5 and 5'10.
Even defenders like Menard, P-O Roy, Schmitt, Lessard have a great impact at 17.
Most of these ''small'' players were impact players even at 16 in the Q at the end of the day.
One team decided to pick the physical mature package in Carruthers and it hasn't paid off so far.
Now, if you give me the choice between equally talented and hard working players and one is 5'6 and the other is 6'1, I will obviously pick the 6'1 guy, but when you're looking at the top prospects, size doesn't really matter for the junior level, the highly talented players will make it.
It's when you get to the depth... teams will want big bodies on the back-end who can play PK to be their #6-7 defenseman, they won't want a risky small offensive D in that role. Same can be said in a bottom 6 for forwards. That's where the size advantage really comes in my opinion, as smaller players that can't really be used in a top 6 role likely won't get the same chances as less skilled players that bring more size and physicality.
Just my opinion.