Achievements in other games are just badges that you did this or that.
The task to get them might be ranging from being easy to extremly difficult, both from a time, brain and fast-clicking perspective.
I don't think winning achievements should be linked to getting a "bonus".
this should be good too for high levels (50+) becouse there are just a few of people to fight and it's boring to find an opponent..
Match making is now depending on the maximum level of your mech.
If you are bored with the higher levels, build a new lower level mech and play there. Might be just as fun as high level