Suggestion on Defense rework

[HEYORI]

Been playing warframe a bit after a while, especially bunch of dark sector defense missions to unlock new "Lethal Alerts". And it was huge "I don't wanna do it" moment for me. 
And I think defense mission type needs a touch from a devteam, it's outdated if you compere it to the rest of the game. 

My suggestion is to treat defense same way as exterminate. Which is:
a) Removing arbitrary "kill all enemies" for the next wave to spawn thing. 
b) Overall shortening time spend between waves, and speeding up defense slightly.

I understand that there is huge issue about hydron and staying in one place spamming 4 play stile. It's complex issue in itself, but making defense not boring would be a nice start tbh.