I get that the organizers want to keep costs down, but at a certain point, doesn't it become silly to shut down city roads and put on a whole marathon just so what, maybe 30 guys and 30 women can race for 2+ hours?
I like the idea someone floated of having a relatively "tough" A standard with expenses paid, a reasonably strong B standard where a qualified athlete can pay for his or her own travel/lodging and a respectable C standard with a ~500 dollar entry or so, split between the race organizers and the USATF.
I think it makes sense to put the A standard at whatever the Olympic A standard is for that cycle- the logic being if it's good enough to compete at the Games, it's good enough to get your expenses covered to run in the selection race. The B standard could be about where the Trials standard is now- gives plenty of guys a strong but doable goal, most of whom would gladly pony up the expenses associated with racing the Trials. Put a C standard up at 2:23-25 or so; that still keeps the field pretty limited and if those guys would like to put up some extra cash to go, more power to them.
I'm just pulling these numbers out of thin air, of course, but honestly, what could possibly be the marginal cost of adding ~60-75 2:15-2:19 guys to a race? So they keep the course open an extra 20 minutes for the statistically likely few who blow up and run 2:30.
Likewise, is the marginal cost of adding another, what, 100? 2:24 marathoners really going to be more than the ~500 dollar entry fee?
On the track, it makes complete sense to keep field sizes limited. There's not that much space, and you wouldn't want to have 40 heats of the men's 1500 because the standard was 3:50 or something. But in a marathon, I've gotta think that the guy running 2:21 isn't getting in the way of the 2:11 winner all that much.