I’m late to the thread but decided to share my opinion; which is worth less than the paper it’s typed on
I’m feeling like the changes to cat 5 / 4 are an attempt to help people get into the sport. I see plenty of cat 5 racers that are riding $5-10K bikes, carbon wheels, have coaches, and are on teams. I think that may be intimidating for new riders to enter the sport.
When I started racing in 1986, there was no cat 5, however many races had “citizens” races. These citizen races were the novice races of the time. They were filled with riders in running shorts, tee shirts, flat pedals and sneakers. Often they were mixed male/female and all ages. They blew apart but it seemed the riders had a blast and got their first races under their belt. Many found the initiative to get a license.
Fields were not small back then for any of the categories. For most races, you would find the race announcements in VeloNews and send your check to the promoter 3 and 4 weeks in advance and hoped it wouldn’t get returned due to a full field. There was no waiting until 11:59 the night before.
There was no requirement to ever do a citizens race, you could get your cat 4 license without ever competing in a race (I never did a citizen race but my wife got her start in them). I don’t believe promoters were required to pay anything to USCF (USA Cycling in the 80’s) for a citizens race or maybe it was a reduced fee. I’m not exactly sure when the cat 5 was introduced, possibly after the merger of USCF and NORBA, but it seems at some point USAC wanted a piece of the citizens action ($$) and created cat 5.
I think it probably worked well at first with little difference than the citizens race but over time I think it has strayed from its original intent. While I believe there are many other factors in the dwindling field sizes in road races, I believe (and hope) this change helps to bring new riders into the sport. I also believe the easing of the category upgrade policy is an attempt to retain riders and keep them interested in the sport longer. Possibly a double edged sword but time will tell.