Against a country that is quasi-cognisant, it won't be undefended. Additionally, half the fun is generally in the flight
to the base, not in getting torn up by ack and WW's
This is especially true in the very hilly maps.
Conducting a well-run noe in a small efficient strike force with a good group of friends is a very enjoyable experience in my mind. Granted, some NOE raids are just gratuitous mobs, but those happen at any altitude.
To be frank, I don't see how taking away NOE stealth would improve gameplay or realism in any way. Just my opinion.