As far as regulatory changes I'm afraid I have no real answers as I don't know if it's quite as simple as that.
That's mostly my view as well. As I observed earlier in the thread, it's not so much about how much fuel you take to begin with, it's what you do when it's running out. It's about having a plan 'A' but also plans 'B', 'C', 'D'...
You could divert early to get to an alternate with reserve plus some holding fuel - problem is, that puts you at the back of the queue behind those who are arriving close or at reserves. Priority only returns once you're in the same boat, so you haven't really gained much.
That difficult-to-define quality 'airmanship' comes into focus in these kind of situations. Running out of fuel in the hold or on the way to somewhere else is not a good option, so it comes right at the end of the list. Reserve fuel is there to be used if necessary to ensure a positive outcome if things have conspired badly against you. You don't initially plan to dig into your precious last half-hour but if unknown/unforeseen factors have come into play, you might have to.
It's also about being able to smoothly fall back to the next option, which may require abandoning some SOPs or contravening day-to-day regulations. When airports become 'full', it normally means they have run out of regular stands and maybe some taxiways. It doesn't necessarily mean you can't land there on a MAYDAY, just that parking might be difficult. Even if there's something stuck on the runway, it might be possible to use the remaining length to stop in. Taxiways themselves can be used as auxiliary runways in extremis. When the poo really hits the extractor, you may have to ignore ATC and just tell them what you're doing. Being mentally prepared to take unorthodox action should you need to is vital, if the remaining options involve a crash...