Why is there a shortage? Well, a number of personnel and policy reasons, most of which don’t apply to the Reserve. The active duty retains this farce that everyone should be in competition to be a future Chief of Staff, while the mathematical reality is that - since the person is generally in that job for three years, only one person is going to make it out of three years (or approx 20,000) newbie accessions. Nor do the vast majority of those people even desire that job, but for a variety of reasons the system compels them to act like they do. Maybe you’d have to experience it to really understand.

The other issues that are more general are that the USAF lacks the capacity to train more pilots - at least in traditional ways. Many of the old primary training bases that once existed have been shut down, their training airspace given up, and the base itself handed over for civilian uses. And generally these were the more desirable bases - like Williams in Tempe - that would minimally impact the local economy because…well, there WAS a local economy, while retaining bases that were sort of on the @$$ end of nowhere (think Laughlin, AFB in Del Rio Tx) but would devastate the region if they were closed down because there was nothing else there.

It was entirely possible for people to do a year in UPT at someplace like Wichita Falls https://en.wikipedia.org/wiki/Wichita_Falls,_Texas , and then a 3 year tour in another desert UPT base like Laughlin as a FAIP (the military equivalent of CFI) before you even saw an operational squadron (which then sent you off to a different desert for unaccompanied tours at nontrivial cost to your family QOL if you actually had one). All the while trying to get you to prepare yourself to be Chief of Staff by prolonged TDYs to places like Squadron Officer School and Air Command and Staff.

Like I said, maybe you’d have to experience it. But like the others have posted, the Reserve is better.