To go first in matchmaking you usually are the lower level player or the player with the lower battle score, right? To give the guy an advantage in the fight by having their turn first.

Why should there be a move move penalty then? It makes going first a detriment instead of advantage because you are get short changed an action point which writes off the match before it even start (especially with opponents 3 or so levels over you and/or having like 70+ health over you as well).

I know i'm probably going to get a bunch of messages say it's to make the match balanced but i seriously have doubts about it since, like dealing with heaters, losing a turn is a match ending situation.

A lower level mech will generally deal less damage, or in your problem case, apply less heat the the enemy mech. To make it fair, the lower level mech is given one action point over the other mech. This can you be used deal some starting damage, deploy a drone as soon as possible or deploy a shield to reduce the incoming damage.

It gives the lower level player a slight advantage, which normally a lower level player will need when faced against a higher level mech.

Why not an extra action point in the beginning if you match with someone that is at least 2 levels higher than you? This way you can do some early damage so you don't burned after your first move.