I don't share the exact same thoughts as the OP but I'm dismayed that the big marathons have increasingly catered to older, richer runners while young, fast runners have to face increasing difficult qualifying times and higher race expenses simply to get on the starting line. Boston and NYC in particular. I would prefer if there were less time qualifier categories, such as a strict under-40 and strict over-40 qualifiers, and maybe an over-50 category. But that's it. As someone in my mid-30s that has vastly improved their mental and pacing game for long races, the 35-39 age group was a comically easy back door for me to get into Boston.
This would help attract faster fields while also perhaps reducing the cost for lodging and travel. Additionally, because the big marathons now are harder for slower runners to get into, it could spur growth in secondary marathons and perhaps a more inclusive marathon in the same metro area at a different time of year. Rather than everyone just gravitating towards the Big 3 and making them increasingly difficult to get into. Distance running is an increasingly upper class hobby and the big marathons are basically the Rich People Olympics at this points.
Also the half marathon distance should way more love than it does. Running a fast one of those is just as impressive and way less grueling than going after the marathon. Running the marathon for most people is just an unnecessary torture fest.