Uh, wh...

OH! You mean the HK tank in the original!

I thought you were talking about the HK Centurion, something which was discarded in Terminator 2's pre-production. Smaller versions also crop up in Terminator 3's pre-production footage.

Hehe... I'm imagining arm cannons replacing the missile launchers on a Wolverine, and I get this:

: Obviously a Scarab gets a pass
: since it provides a pretty immediate argument for its value as a
: super-weapon, badass visual, and fun gameplay.

True.
Also, I think the Covenant culture and technology level combine to make bad ideas feasible. Like the energy swords: Swords are generally a bad idea on the battlefield, but the Covenant have energy shields which let them weather hails of gunfire, the swords rely on focused plasma to burn through material rather than any sort of cutting edge, and they can collapse to the size of a lightsaber hilt when out of use.

: The UNSC just always seemed
: rooted in some real-world military - an extension of what we have today.
: But a mech breaks that for me, and feels more like a sci-fi trope shoved
: in without a need.

=D