DC has written
there already is a size limit for weapon skins so you can only add rather small lasers.
lasers give you an advantage because you see enemies earlier (because you see the laser). it's like cheating.
They can still be edited to be as long as the 1st one which is really unfair. Files should be as big as 32x32, letting 'cheaters' make lasers just as long as an AWP which would be quite 'harmless'.