And then an infantryman with a armour piercing weapon shoots a leg joint and ruins the entire beslubbering thing.
Granted, that's already a problem with wheels and treads, but at least the consequence there is "merely" immobility, and not falling over.
There is *one* advantage I could imagine, and that is as a kind of rapid, lightly armoured heavy weapons platform, acting in support of infantry and mech-inf units. And then there's the BigDog robot from DARPA, which I think looks promising, sure, it's just an automated pack mule, but honestly that is probably a lot more useful than giant robots constantly threatening to trip over due to ground pressure, exposed joints, complex (and thus error-prone) machinery and a high center of gravity.
I mean, the jerry-can revolutionized warfare, the Panzer VII Maus didn't.