the way I see it fliers are very useful and durable, and it's not strictly about the odds of them getting hit, it's also a mind game with your opponent.
If you field several vehicles, say a monolith, a ghost ark with immortals and a nightscythe and your opponet has, say 6 dedicated anti vehicle weapons (lascannons/missile launchers). And you bring your night scythe in, he has to decide if it's even worth trying to shoot at it rather than your other vehicles. He'll on average only hit the night scythe with only 1 of his 6 heavy weapons, and even then it's not guarenteed he'll be able to stop it (especially if youre using evasive manuvers for the jink save). You've also got 2 other transports on the board (ghost ark and monolith portal) that he could shoot instead with a much better chance of actually hitting them.
So if you provide your opponent with a number of targets, and use proper positioning, I find it unlikely that he'll dedicate a lot of firepower to trying to take down a flier, and if he does then he's not bothering the rest of your vehicles.
And as mentioned above if you just use the nightscythe to drop off an inexpensive unit to take down a specific target, you can just use the flier as a very mobile tesla destructor, which is a great weapon and it's unlikely your opponent will dedicate a lot of fire to take down a transport that has already dumped its cargo, even if its weapon is still a threat.