So why does DBG offer Flanker Armor for sale for Lightnings when it doesn't save the vehicle from 2 bricks of C4? Why restrict to C4 in the first place and not include rockets?
It was a oversight when they nerfed vehicles in CAI. Since it's a vehicle the level of attention from the devs is "What's a lightning?".
Because CAI contains many significant design mistakes. Flanker Armor is just one. After all how could anyone believe current situation is ok, when many 1 vs 1 vehicle duels end up with one of the pilots bailing out to throw a C4 brick? And last update didn't change a thing, it's not like 0,4 seconds of arming time make a difference. This is Planetside: C4 > everything.
I know, but it won't change the state of the vehicles game. The super remote controlled anti-everything grenade remains the go-to weapon for most of situation, either you face infantry, Max or vehicles. The problem with the state of the game is anti-c4 items are simply not effective enough. Flanker Armor on Lightning in particular is just stupid: even when maxed it doesn't grant survival to 1 brick unless you are full health. 2 bricks are instadeath anyway, without considering the Rocklet that adds extra damage.
Actually, C4 deal 2500 damage to a stock lightning (4000 health), so you can survive to 1 brick. But I agree with your conclusion : as long as c4 can kill a flanker armor lightning in 2 brick, flanker armor will be useless.
Against a LA you must also take the Rocklet into account. Yiu can survive 1 brick + rocklet shots only if you are full health. Going around with 75% health is high chance to die in 2 seconds.