MGSV supposed has well over an hour of main story cutscenes over MGS4. Not sure how people are feeling otherwise. I agree that MGSV doesn't feel like a suitable ending to the Metal Gear legacy, but I knew this was going to be the case when Ground Zeroes decided to make a sudden shift from campy B-movie sci-fi spy nonsense to super serious cringe-worthy grittiness.
It becomes obvious why David Hayter couldn't voice this Snake. The incongruent nature would have been even more striking. On top of that, Kojima continues to try and retcon/reexplain/deconstruct/demystify things that would have left a nice bit of flare on the whole series if he'd left them alone. The final reveal being probably the most disappointing to me, making me feel like all of my actions in the game are pretty much pointless.