1) If the engine guard is removed, is there any other protection to the engine from below?
You either win or lose, you cant have both!
If you need the GC, remove the plastic guard. If you need the protection, let it be.
Anyways, it is just a plastic guard and even if it does scrape, it is easy and cheap to replace.
People here like me drive Civics on Indian roads which has no engine guard and next to nothing GC. Not a big deal!
2) Try convincing the ignorant rich folks who will definitely want to exhibit the macho image of an SUV. You and I know that XUV and others like Duster/Terrano /Avventura are crossovers, only meant to be taken to the occasional grassy patch off road, but also be able to perform reasonably well on dry dirt surfaces. In India, as you would appreciate, any excursion involving off the city roads has a situation where you need to hit the road shoulder to avoid oncoming tractors/trucks/buffaloes etc. At that time, that additional GC/ overhang/approach/departure angle plays an important role.
If the owner tries such stunts on purpose, even a plastic guard will not be able to reduce the damage.
Rest assured, the XUV has a pretty healthy GC and no owners have complained about the underbody getting hit.