Wilson, if we were expected to be totally realistic about this, I doubt anyone would even bother with walkers/mechs. They're a terribly inefficient concept. Why bother giving a spacecraft legs and arms, rather than just mounting any of its weapons on a swivel mount? And I'm a bit surprised you put 'artifical gravitational plating' on the realistic side of the mech/mecha dynamic.

With regards to punching things apart in space, it sounds like you've got something in particular in mind that's earned your disgust. In the defense (however moderate it may be) of mecha anime, some make an honest effort to justify their close engagement ranges. Gundam had the Minovsky particle, for example; which was a hypothetical byproduct of helium-3 fusion reactions that made most electromagnetic sensors (radar, microwave, etc.) inoperable in regions saturated with M-particles. The mecha themselves ran on fusion reactors that spat M-particles out, which made actually locating them by non-visual means rather difficult. I'm not saying all of Gundam makes scientific sense (it seems the further you get from the original series, the less sense it makes), or that all mecha anime try to be even a little realistic, but not all of them are as brainless as "CHECK OUT OUR BADASS ROBOTS PUNCHING THE !@#$ OUT OF JUPITER! NANANA GUITARSOLO!"

/spiel