FBinNY 

This isn't an argument, simply a difference in worldview. FWIW- some 50 years ago I set up my old 10s (2x5) with a 51/15 high gear. It was more than adequate 99% of the time, and the few times I ran out of RPM it was in conditions where I might as well be coasting. So we're not in disagreement on gearing philosophy.

That said, the OP's current high gear is roughly 25% lower than what's been standard OEM for 30 years or so. The OP came here stating that he is only using the top three gears for his 2 to 20 mile commute, and asking for technical (mechanical) advice about going to higher gearing. Given that he now only has a 3-speed (effectively) it's not an unreasonable question.

Yes, in the long term the OP can, should, and might increase his cadence to where his current setup id fine, but that's not today or even next month. Nor is it it necessary for casual riders, to ever develop high cadence for the amount of riding they actually do. I suspect that a cadence ranging from 60-80 would put the OP in a high percentile among riders at his level.

So, (here's the worldview issue) when riders come to the bicycle mechanics forum looking for practical, mechanically sound methods of getting their bicycles working, or adapted to their (perceived) needs, we should try to provide that info, rather than lectures about how they NEED to improve their cycling technique. Doesn't mean we can't or shouldn't suggest the related stuff, just that we need to respect them at their current level, and answer the question asked.

It's been my experience that newer riders get stronger before they get faster. That means they'll be pushing relatively higher gears for a while as they progress and mature in cycling skills. If their bicycles don't suit them at their current level, it's a tossup whether they'll put in the effort to improve or simply quit altogether. If we don't help them to enjoy cycling now (however they do it) they won't stay around to improve in the future.