there is a mod called Melee Mover which helps ALOT with vanilla melee frustration.
it allows one to melee a target that is within sprint range...that means no more only being able to lwak up to target.
you can get up to full evasion pips when doing a melee.
also it allows one to pick a direction from which to attack just like the AI (depending on terrain)
in most cases you will have a choice of three directions from which to melee even when doing a DFA.
so melee mover kinda lets you charge it just doesnt give you the charging multiplier.
it is due mostly to how they do melee combat in BT (it is random whether your mech will punch, kick or shoulder/head butt target)
so proper charging and jumping in to melee are off the table unitl melee combat system is revised in this game.
but until then this great mod relieves some of the issues with it