Slat armor, specifically meant to counter HEAT warheads.https://en.wikipedia.org/wiki/Slat_armor>>17478407
Because once you start removing limbs from a mobile suit, it becomes questionable whether it's a mobile suit at all. If it's going to have thrusters instead of limbs, why even classify it or have it operate as a mobile suit when it'll handle more like a mobile armor in space use? Most mecha designers opt to just have thrusters mounted on the limbs to have the best of both worlds.
In regards to a smaller profile, later on they develop fire support models that also incorporate treads and thrusters in a fairly small but lightly armored package. They have a vehicle mode that has a squatter profile and a humanoid mode for height advantages when needed.