I would most definently pilot a Quad mech for a variety of reasons. However, they have soo many other things to add before they can even think about how to balance+add quad mechs. Is Mechwarrior 2 the only mech game that has added a quad before? Even in Mechwarrior 2 it piloted like a normal mech (an incredibly underpowered one at that because of it's huge size for being a light, while having poor weapons).
2 of my top 10 favorite mech designs are quad mechs. (Jaguar and Thunder Fox), with the rest of Quad mechs ranking pretty high on my favorites.
However unless we get a jump to the future we only have the following available to us in 3050:
Xanthos, Thunder Stallion, Snow Fox, Scorpion, Goliath, Fire Scorpion
Though if you go by the 3 Variant rule and exclude variants that have tech we do not have access to right now:
Goliath....... Maybe Scorpion if you include 12S and 1O, while they have stuff we have access to now, they were made after 3050.
Even though, Both the Goliath and Scorpion are Unseen from Dougram.
We'll just have to hope for a jump to the future. Though, Smoke Jaguar kind of prevents that since Smoke Jaguar "dies" in 3060, even if there will be more Smoke Jaguar warrior being found for quite a while longer (Up until the Dark age according to Sarna).
It's possible to have Quads in MWO, but one things for sure, you'll have to be waiting many many years before we get to use any quads..... I'd be happy playing with the majority of the Quads. We'll just have to stick with Bipeds for now.
Besides, I really doubt they'd make it so Quads could do somethings they could in the fluff like sidestepping.
I'll be hoping, but very very slightly because it's so unlikely.