Just buy the shoes wrote:
If you can afford the huge entry fee to Boston and an expensive weekend in a hotel, just go ahead and buy the damn shoes.
This type of reasoning doesn't make sense (or other posters saying that everybody who can afford to do the race in the first place can afford more expensive shoes).
Among all the people who would otherwise run Boston, there is a spectrum of wealthiness. Some have so much money that a couple of hundred extra is of no consequence to them. At the lower end, some people might have decided they can JUST BARELY pull off this Boston thing if they save up and scrape their money together and cut costs wherever possible. An expensive pair of shoes would put them over the line.
Also, many people running a qualifying marathon live in the area. That's what I've always done - run the local city marathon.
The course isn't perfect, but it's OK. Basically, I can qualify for Boston for a $100 or so investment, running a race that I probably would have run anyway. Adding in $250 shoes would be a no-go.
Look at the same basic issue but from another angle: high school running. What if in the future, all the well-to-do kids have expensive shoes that give an ACTUAL advantage of a few percent in races, while the rank-and-file kids have to make do with the usual old stuff.