Well, I think it's mostly about being loyal "to the end", in a sense... People liked Kojima and his take on Metal Gear, and if he was indeed fired like it seems to be the case, people aren't necesarily willing to encourage such behaviour and give money to the guys that fired their favorite franchise's creator..
Personally, I was more than willing to accept MGSV was Kojima's last MGS game and I kinda hoped it would tie everything and be the last MGS game (although I do want a MG1 and MG2:SS Remake down the road)... But the way it's being done, kinda makes me want to boycott any future MGS title...
But really, the thing I really care about with all of this is not MGSV, or MGS sequels... IT'S P.T / Silent Hills... I wanted that game so bad, and now that it's on the chopping block with very small odds of ever being completed, I feel terrible.
I'm actually kinda happy for Kojima... He has enough notoriety to be able to crowdfund a studio, and in a couple of years, he'll be doing exactly the game he wanted to make all along without having to take orders from suits at Konami... If there's one person that I know is capable to build a game and game studio from the ground up ,it's Kojima... Heck, he built Kojima Production L.A recently, he built his own custom engine ... He can do this no problem.