You are quite right. The masses are happy with USB 3.0. Not all find it sufficient.
https://thunderbolttechnology.net/tech/how-it-works
The more you understand TB, the less you will tout USB 3.0 as "good enough".
Having superior technology unfortunately does not automatically guarantee widespread market adoption (there are a few examples of that); there are more factors that come into play, such as licensing fees, timing, or politics by potential backers. I'm not going to speculate here, where APPLE and/or INTEL miscalculated, but it is a disappointing fact of life nevertheless, for many people, who for obvious reasons, expect the best tech to prevail.
Myself, I am also a happy supporter of TB, as I believe it to be the best I/O technology out there at the moment, with the greatest
potential for future universal connectivity (after a few years of legacy support, of course).
But I have found there to be many Thunderbolt 'naysayers' out there. Not meaning to sound pessimistic, but defending this awesome new technology here, is as useless as carrying water to the ocean. Granted, USB3 is indeed more than sufficient, at this time, for most ordinary tasks, but with an eye towards the future, I'd say, TB's advantages will become more pronounced, as it's true peer-to-peer design and it's multi-lane, bi-directional I/O protocol, coupled with future envisioned speeds, has the greatest potential.
Without wanting to sound 'elitist' here, those who don't need it, can happily use the admittedly, less expensive, but arguably, 'lowest common denominator' technology. Some of those who
appreciate,
and need it's awesome capabilities, are using it now, and don't need to be convinced anymore.
They are indeed more hoping for a somewhat wider adoption to lead to
more availability and lower prices.