By that definition reality is completely subjective which rather plays towards my point.
You find the axiomatic basis of scientific understanding to not belong to "practical knowledge". Or that the axiomatic nature of standard logics is not practical? So basically all of physical science, mathematics, logic, ... understanding the epistemological basis of these things is impractical? Because? On such a position theoretical physics would seem to be 'impractical' and not something to concern ourselves [humankind] with - the advances in theoretical physics in the last century or so have worked themselves in to almost all areas of modern 'Western' life.
And we do agree that reality is subjective; it's just that if a facet of reality is only perceived by a small fraction of the population, its value is insignificant to most. The value of reality is in its adoption as a foundation for communication.
Simple example that many people use day-to-day is relativity and GPS (eg http://www.astronomy.ohio-state.edu/~pogge/Ast162/Unit5/gps.... <- that's just the first likely looking Google result for GPS+relativity, feel free to look for yourself).
I guess things like transistors, fibre optics, nuclear power, and lasers are so far removed from everyday life that theoretical physics simply has no application to reality. /sarcasm
Why do you trust sense-data to be real? Brains in vats, holosuites, yada-yada ...