Everyone I talk to that is waiting on the 3ds are simply waiting for Zelda, kid icarus, or a mario game. The 3ds already had record breaking preorder sales but how much bigger would they be if Nintendo released a Mario,  Zelda, or  kid icarus game at launch.

kid icarus would give a big insignificant increase as thats for more hardcore nintendo fans who would preorder anyway.

Zelda would give a small incrase.

Mario would have given a big boost.

All in my opinion

It's important to space out big releases - it would have increased preorders, but long-term sales would have been affected with all of the big names straight away.

I think that Nintendo should've put either Paper Mario or Zelda OoT for the system's launch, but IMO the line up is decent enought at the moment, with titles like Street Fighter, Ridge Racer, Pilotwings, Nintendogs and in Japan Prof Layton.

Well, seeing as how they basically sold most of their initial shipments, I'd say higher pre-orders would've just meant more disappointed people 'cos Nintendo wouldn't have been able to supply enough systems.

Pretty much this.  There couldn't have been that much hardware to preorder that was available for it.  Also, anyone who did pre-order it knew those games would be coming in due time.