This thread makes for odd reading.
I'm surprised nobody has stated the obvious (at least seems that way to me) - the tournament was poor because the teams in it were poor.
France were blunted up front by Giroud and Deschamps stubborn approach, Spain are at / past the end of their cycle, Germany were below standard and like France lacking in firepower and form up front, Italy are average as fuck and so on and so on.
The shit games (of which there were many) were generally due to one of the teams acknowledging their inferiority up front and playing the game accordingly. Players are fitter now, sure, but teams are also more tactically disciplined and aware. The only way to mitigate against that is to disincentivize that approach to the point where it gives the better sides an even greater advantage than they already start the game with.
The Bielsa (or whoever you want to credit it to) school of football is definitely in vogue right now and it's fair to say that luxury players that don't or won't work hard for the team first and foremost are less likely to be accommodated than they perhaps used to be. But football is cyclical and things will probably change.
It might be that at international level teams are finding it harder to find balance than teams at club level. I've not heard such complaints about the CL.