I think it has to be a balance between encouraging participation and just a qualifier for the Olympics. I don't mind the fact that extra runners are allowed, in fact I think it's part of the charm, because the marathon is inherently a large community event.
But as the standard of American marathoning improves, the qualifying times should also improve. The best American marathoners are faster than they were 4 years ago, and honestly they're probably more than 2 minutes faster.
The fastest time in the post-Olympic window that I could find was Scott Fauble's 2:08:52, and most marathoners were much slower than that, in the low 2:09s on a good day, or even the 2:10s, 2:11s. And that actually played out all the way to Olympic Qualifying time. People will famously remember that the US struggled all cycle to get men to meet the Olympic standard and only 2 men eventually got the Olympic standard of 2:08:10, Conner Mantz and Clayton Young.
Now the fastest marathoner is 2:05 low with a bunch of marathoners packed up in the 2:07, 2:08 range. Like last cycle, we expect times to speed up as we get closer to the Olympics and prospective Olympians have to meet the Olympic Standard, which early rumor says will go from 2:08:10 to 2:06:30. It's possible a bunch of guys run 2:07s, 2:06s in this upcoming cycle, and the American Record may also fall.
Part of the prestige of the event is not only that you are one of the top 200 or so marathoners in the world, but also that you run a time that is considered "elite" in the context of what is being run by the rest of the country, including the top performers. That's why I think it makes sense to raise the National Standard, and the Olympic standard is also being raised by almost 2 min as well.
But I think, while amateurs are certainly going to be grumpy today, they're also going to raise the bar. If you're really a 2:20 guy, 2:15:59 is not unattainable. And even if you specifically don't get it, someone in your friend group who is also a 2:20 guy is probably going to rise to the occasion. I suspect with the influx of college marathoners at the top level and amateurs raising the standard from the middle, we may still end up with a field size in the 150-200 range.