I'm in the same dilemma as the OP.
I've geared my DR650 so much toward the highway that the one time I did actually really try to wheelie the damned thing only came up about 4 inches.
Would I like to have the skill to wheelie? Yes.
Do I think that at 42 years of age it's something I want to chance with bikes that just aren't suited for it? No. (Not saying the DR650 isn't a wheelie king - but mine isn't just since I have gears that allow me to easily do 90 and 100 MPH to try to keep up with south Florida traffic on the super-slabs).
If I've ever given free reign on a 250cc dirt bike, and soft ground, I'm sure I'll try it... but until then I just won't.
I still get air time from smaller jumps and shit, but that's easier.
"After reading through this thread I've come to the conclusion
that more people cruise the internet looking for reasons why
X bike won't work in Y scenario rather than actually riding
their motorcycles." -- RyanR