Being taught to rotate
In answer to the question above, for odd reasons, I did my PPL training (2011-12) in two different flight schools.
One was a commercial airport in East Anglia, flew C172's off a long concrete runway and had a number of youngish instructors. Most definitely they drummed into students about 'rotation speed', even the learned by rote safety briefing to be given prior to pulling on to the runway had to refer to 'At x knots we will rotate'.
The grass strip that I had started at and at which I finished my PPL (in a C150/152) had a 'more mature' instructor whose instruction was get the front wheel off the ground asap, then let the plane fly itself off when ready, using ground effect as an ally.
I guess both have their place in the right situations.