The primary reason for using FOSS has always been freedom: it's right there in the first letter of the term. Technical superiority has never been the primary reason; it's just always been assumed by some that technical superiority would be a natural byproduct of lots of people working together on a project without a profit motive, but there's really no evidence supporting that. FOSS applications have usually (but not always) been behind their proprietary counterparts, because a for-profit company can afford to pay people to work fulltime on something they might not be all that interested in. There are some exceptions where FOSS software has been class-leading, but I don't think it's really the norm, although I do believe the overall ecosystem is much better for various reasons.
It may be (and always felt to me this way) that technical superiority is only one dimension of the problem.
For example the reason I keep using Linux on my machines is not because the OS works better for me -- it definitely does not. Things are crashing or doing stupid things and the entire ecosystem is completely disjoint and not integrated very well.
The reason I use Linux on my desktops is because I know I own the machine and it is doing my bidding (mostly, if we forget about the hardware part...) It is knowledge that if there is a problem there is a path to fix it -- it just depends on how much effort I am willing to expend.
