People already said why they don't like the 3 minute defense if you would've just read what people wrote. I personally don't like waiting for the drone either. The 2nd and 3rd stages of the bounty are BORING, you sit there for 3 minutes while nothing happens and then you have to follow a drone that is excruciatingly slow, I can go trough the entire open world of POE from one corner to another and come back (on foot, no archwing) and the drone would still be going to the boil. This guy puts it very simply:
Warframe is a fast paced game where speed is integral to the game itself, so adding a mechanic that completely makes you stop and wait for no reason goes against the entire point of the game. There's a reason people don't like playing defense and mobile defense, the enemies spawn too slowly and there's no way to speed it up but people like survival because there's a constant stream of things to kill even though that has a forced timer as well and the entire gamemode is based off of you killing things fast since if you don't you run out of life support and fail the mission.
