My take is, a given configuration is not better generally, but as several posters mention or imply, there are pros and cons that must be weighed case by case.
I have settled on 6-speed as my sweet spot, given the vintage of frames that I like and like me back, not to mention my penchant for half-step plus granny gearing with my <patent pending> natural progression 13-28 freewheel layout.
Regarding frame adaptability, one of my original 6-spd bikes recently swallowed a 7spd freewheel between the dropouts with no complaint or modification, as I converted it to 2x7 brifters for my son's benefit.