I have no doubt that if it wasn't for shorter, tight turning skis I would still be on the groomers. Maybe even taking lessons to improve my high speed carves. Instead I'm having fun on the bumps and in the trees.
So yes, at least for me, ski design has made lessons obsolete.
Maybe this is an example of how ski instruction needs to evolve in order to stay relevant. I get the impression that most people in North America think that instruction is only about learning how to ski better on the groomers and everything else is up to you to learn yourself.
Like you, I'm not willing to take lessons specifically to improve my carving. But, I am willing to take off-piste courses in the Alps to improve my skiing in variable terrain/conditions (as one guide told me, if you can't ski crust, then you can't really ski). A happy side effect is that, as I improve off piste, skiing on piste gets even easier.
Maybe ski schools need to offer more group courses and individual lessons that are focused entirely on skiing ungroomed terrain. That way, intermediates and advanced skiers can learn to enjoy their favorite terrain even more, or at the very least they can have someone taking them around the mountain to the best terrain/snow.