Really ... you wanted the wall of text?
Go to the Blake Sea, roads, or some of the other mainland areas that are commonly used by vehicles and look. In the Blake Sea there are generally more people hanging out on islands than are actually moving, and the total number of people isn't that large anyway. Now consider that the Blake Sea and the other areas are a small part of mainland, so you can't claim that there are so many of those areas that the overall total is significant. I'm only specifying mainland since estates can easily ban or regulate orbs if they wish.
Would you leave SL because you couldn't fly over someone's parcel? For that matter, isn't it likely that region crossings are a far bigger problem for vehicle owners than some parcels they can't enter? What percentage of vehicle owners would leave SL because of security orbs?
Niche case isn't dismissive. Modifying the simulator code to add a feature that would only be used in a fraction of SL is a niche case. It's also not that easy a feature to implement. How do you keep someone from building within an altitude range, considering that you still would have to allow vehicles? You could block non-physical objects from being within the range, but not all vehicles are physical. You could decide that anything that's in the range for more than X seconds must be static and therefore get rid of the object, but what about slow-moving vehicles? You could allow everyone's objects to enter *except* for the parcel owner's, but it doesn't seem fair that the parcel owner couldn't fly over their own parcel within the corridor. For that matter, what happens to parcel permissions within that range? To be fair to the parcel owner, the people passing through that range shouldn't be able to see anyone above or below if the parcel is set to not show avatars. Is the corridor set for public ''allow entry" and "allow scripts" even if the parcel isn't? Is doing all this worth the risk of making the simulator code less stable?
The security orb disagreement doesn't really have a solution. LL can't change LSL to stop zero-second orbs, because separate functions do the detection and the ejection. They could add something to the TOS (applicable to mainland only), but what delay value would be reasonable? I discourage the use of orbs at ground level on my region, but if used they must have at least a 10-second delay. For some vehicle users that's OK, for others it's unacceptable. If the land owner is dealing with a stalker then perhaps a very short delay is OK, but anything more is unacceptable. If LL requires too large of a delay, they *will* lose people who need the security. It's not likely they'd lose vehicle owners by leaving things as they are since vehicle owners already have the problem with orbs and they're still here.
And finally ... One positive thing that could be done without messing with the simulator code is add OpenSpace (I assume LL can still create them) regions so vehicles have better channels and more places to go. If LL wanted to offset the cost of running the regions, they could charge for using them. It doesn't solve the security orb disagreement, but it does meet one of the biggest desires of vehicle owners (other than making region crossings seamless). It would also be nice if LL would set some standards for themselves & the moles for the width of channels.