Patlabor addresses this somewhat. Bipedal mech started as a way to rapidly rebuild Tokyo after a massive earthquake. They became so ubiquitous, that regular people had access to them so between drunk/disgruntled construction workers and some bank robberies, Tokyo police had to add two divisions of "Patrol Labors" to deal with it. They're costly and annoying to everyone. The mech carriers are two lanes wide and no body likes giving them the right of way in traffic. After that, the companies making them diversified into military and meches have a limited roll depending on the terrain. Mostly swampy jungles with bad line of sights, so the legs are useful and the high profile a none issue. High end military models are very quiet compared to civilian models.

Ah but the bipedal mech suits could crawl along to floor, given a really low profile. Tank can't do that. Checkmate.

/s

I think you are ignoring the very important fact that Gundams are dope.

In game they introduced regular human sized battlesuits ("elementals"), they gimp mechs pretty much as bad as you're saying.

Let alone drones. If you don't install OP point defence on every mech, they will all be brought down by drones targetting the legs.

A taller mech has better reach. It helps when fighting with fists and swords. Checkmate!