The more electronics RVS have, they more you need a surge protector. Modern RVs are very electronics heavy - fridge motherboard, AC units, TVs, microwaves, and some detectors can all be adversely effected by bad power.
I agree, LOW voltage is much more frequent than high voltage or a surge. Progressives protects high/low voltage and will allow power through when the power situation returns to normal voltage. A quality unit will be expensive and may you never need it. I never plug in without one. I know how many times it has saved me but wonder how many more times it activated when I was sleeping or gone. Happy Trails!
FYI - I think the whole house unit referred to here is one that protects the entire RV(house), inline prior to power entering the RV.