I see all of your points but I disagree regarding the game from 2005 compared to the last three years. It's much faster and skilled and the stick work a great deal less. Having said that, I still don't believe a goalie has been the reason a time won the cup in many many years. It's been speed, skill and depth. None of the top 6 paid goalies in the NHL have won the Stanley Cup. So is it the best places to spend the money?
Holtby was top 6 in cap hit and he just won a cup. He has a Vezina and another runner up finish, he is one of the top 5 goalies in the league. Sure he didn't have his best regular season last year but he came in and settled things down against the Blue Jackets and was a big reason they got through round one. Also a .922 performance in the playoffs is an excellent performance, he was a key part of them winning.
Crawford had the 6th highest cap hit among goalies in 2015 when they won the cup. He also had a very strong playoffs with a .924 that year
Unfortunately cap friendly doesn't go back far enough to check before 2015 but Quick has two cups and had a cap hit of 5.8 million (300K less then Helle) so I would wager that he was in the top 5 or so in cap hit during those years.
So yes I would say that teams that spent good money on good goalies where far better for it and it played a big role in their cup wins. Helle is paid within half a million 300K of two/two time cup winners in Crawford/Quick and about 60k more then the recent cup winner in Holtby. Money well spent imo.
Edit:
Goaltending performances of cup winners:
Holtby .922
Murray .937 and MAF .924
Murray .923
Crawford .924
Quick .911
Crawford .932
Quick .946
Thomas .940
Niemi .910
MAF .908
So in the last 10 years teams that have won have received upper echelon starting goaltending performances in 7 of those years. Only 3 teams have been able to overcome sub par playoff goaltending to win.
Goaltending is just like any other position, in order to win the cup your number one goalie will in most cases need to be performing at a very high level. Just as your skill forwards and defenseman will need to be performing at a high level.
All components firing at the same time are critical to winning. You don't want to have your goalie steal you a cup but you want him to perform well all the same.