Stranger Things Ending (Spoilers!!!!)

Ok guys, I disliked the ending a lot. There are still so many plot holes and mistakes. Where are Derek’s parents? What happened with Mr.Clark? If killing the mindflayer was so easy, why didn’t they kill it earlier? They all knew that Vecna was there, below the heart. Why didn’t they decide to do something against him earlier? So much was so unnecessary…. And apparently, there’s a spin off coming too?? With complete new characters that somehow are connected to the current ones??

Why didn’t they let Steve die? Why only Kali? 

Why did they queerbait Will so much??