I never understood the non-Omni thing. I'd imagine omnis to be in high demand, and since there were only a hand full in production, most in the DC, I would have thought the FedCom states to be chomping at the bit to get one produced domestically that could compete with the Avatar and Sunder and so on (though granted the Thanatos is faster, so different in that regard). They did go on to make the Templar and Hauptman, so clearly they weren't entirely over omnis.
As to the mech, it's in a class I like, so it's not without its uses, and I did actually enjoy MW4 at the time so I don't have bad memories of it (though I never used it since I went for the assaults quick as I could, like everyone else). But most of its variants just don't do it for me. MRMs aren't useless, but you either need a solid C3 network, which is hard to put together outside the DCMS, or you need to get in close, which is fine for this application, but not usually what I need to look for. Reminds me a lot of the Lao Hu in its way, though I don't like it as well.