(Thanks: Mayonnaise, Amasawa, etc)
When low % games were first being talked about, someone announced that the
Thermal Visor isn't actually needed to beat the game. However, it seemed to be
theory. Amasawa played through the game without it and the rest is history, 28%
was the new low.
There's not much to skipping the Thermal Visor, you just don't get it; leave the
pirate base after getting the Super Missile if you don't intend on getting the
Ice Beam and Gravity Suit early. All of the power conduits in the game can be
activated if you know where to shoot, and Thardus can be beaten by manual aiming
(it's not really any harder).
Metroid Prime's second form can also be beaten without the visor. He eventually
switches out of thermal view, although you can still damage him in it anyway,
even if you can't see him.