A couple of issues have been brought up.
The reason that doing it by feel is not a good overall approach is that it assumes that the die is correct for the chamber. It may not be, and if it is a little too big, you will end up pushing the shoulder too far back to get the feel you want.
Being able to get away with a bump die is strictly an issue of how much pressure you load to. Generally, I am on the side of closely fitted FL dies, used every loading, but to be fair, a friend, who uses a grain less powder than I in his PPC has gotten many firings with just bumping. With my load (more typical), I cannot. Looking at his results, I may try his load
As to types of gauges, I prefer those that yield measurements in thousandths, over the Wilson variety, particularly since I am shooting for a .001 bump, for most of my applications.
When I set up a die for bump, I use a reference case that has been fired till the shoulder to head measurement has stabilized at its maximum, not a once fired case, and I use a punch to remove the primer before measuring. The primer can easily spoil your precision, with even a slight crater or protrusion.
As to how we got buy all those years without gauges... In the past, dies that were in common use were of the one piece, expander ball variety, that over sized the whole case, and may not have even been able to bump the shoulder of a fired case. Because many calibers (like the '06) have a relatively small shoulder angle, they will chamber without much effort, even if the shoulder is not bumped, as long as the body has plenty of clearance. A die manufacturer once told me that what made small base dies different was not necessarily that they were smaller at the base, but that they were short enough to allow shoulder bumping sufficient for sizing cases for the requirements of a semiautomatic rifle. Given this, it is not coincidental that something like a Wilson gauge is an integral part of setting up one of these dies for a Garand or M1A, where generous bump is required, and the dies will allow for that to be over done.
As an aside, let me say that I am always amused by reloaders that agonize about a tenth of a grain of powder, and are so sloppy about other aspects of their reloading that may matter more for obtaining best accuracy. It is a common phenomenon.
One last piece of advice...Straighten out a large paper clip and bend 1/8" of one end at 90 degrees. Learn how to use this "tool" to feel the interior groove, near the base of a case, that is a positive indication that excessive stretching has weakened a case. Cases that fail this test should have their necks crushed (to prevent its being retrieved and reused) and be discarded.