nop.
It is shown in battles, because their appearance is random, so obviously people need to know where it is.
In Siege, it's always in the same place. And if defenders could always see it and check if it's going down, it will prevent succesfull ninja rush from attackers, wich is a fun part of the game.
I don't see how seeing the flag will make the game more enjoyable :
-new attackers just follow others till the flag, no problem.
-new defenders take time when they're dead to look at the map and see where the flag is. Easy.