Support is "better" because in the game's current form it is an overpowered perk with no weaknesses. This doesn't mean commando is useless.
Yes, if winning is your only objective it is wise to have 3-4 supports on a team. However, if someone wants to play commando there is nothing wrong with that, as a great commando is a very important member of any squad. There is a reason why as commando I'll end up with more kills than any support I'm playing with, and it's not because I'm some amazing player who is on a level above everyone else.
Support is not perfect. No weakness?
They fear husks which consists a huge part of the enemy troops.
They are low(at least relatively low) on ammo.
Their weapon costs most($1200+224+300 for AA12+HS+katana, let alone that they usually need 20 extra shells for HS which costs $300.).
As a comparison, let's take a look at commando:
They fear FPs and SCs(No, we are not talking about PAT). They consists a small part of the enemy troops.
They are highest on ammo(750 rds).
Their weapon costs moderate($750+300+90 for SCAR+AK+MP7)
PS: Health bar means better performance on dark maps (such as bedlam), but let's just neglect it.
Commando ain't no weaker than support. Support is more likely a "Good for all" perk so they can handle any situation. But it's not the right way to use it as support*3+. Players think support strong cause they just handle everything. That is prejudice. KF is a coop game and support*6 means no coop. It ain't work like that.
PS again: If there are more than 3 support in the game,then continuity and husks will become a real problem!