You have made some good points here and I agree that he is a very good captain but he gets overrated a lot for his batting as well.
As far as the 2019 World Cup is concerned, him getting the MOTH award ahead of Stokes was daylight robbery.
New Zealand had an excellent bowling attack for English weather. They still do. Making the final was not something unexpected.
Ultimately, New Zealand were response for their own faith. They had the opportunity to eliminate England in the league phase but produced arguably the most cowardly performance of the World Cup at Chester-le-Street.
They needed 306 to win on a very good batting surface and they showed zero intention, ultimately perishing for 186 in 45 overs with none of their top 4 including Williamson striking at above 60.
England would have been eliminated had New Zealand won that match.
In the final, they had so many opportunities to put the game to bed. They were very timid with the bat, they had England on the ropes at 86/4 but allowed Buttler and Stokes to forge a partnership and his captaincy was very ordinary in that phase.
1) I agree on his batting being overrated. No complaints here.
2) Again agreed, Stokes deserved it.
3) Disagree here, their bowling attack was good, but it was overrated. Pakistan handled it just fine and so did England in group stages and other teams. Their batting was more toothless, It's just NZ played just alright and decent enough to barely squeeze into the top 4, and from their India mentality was shot as always.
4) Again disagree, England was leagues ahead of them, 2019 England is the strongest English odi side in history, They had no chance, however I agree in the final, Letting stokes off the hook especially that catch that went for a 6 was their own fault, But the deflection and Super over rule was unfair. I can get behind the deflection rule but not the Super over rule.
Williamson ultimately managed to defeat a 2015 Australia that would beat any odi team in history except for their own classic 2003 and 2007 self and no other team managed to defeat that team, to top it off he went unbeaten till the finals.
Yes the victory against australia was honestly a fluke in group stages and in the finals, it was impossible to replicate it 2x, australia put them in their place, But 2015 was 100% his peak, managing to win that many games despite 2015 squad being one of the weakest NZ squads in a world cup.