I was at that race long long a go. I went to it again this year, it is very different. (It was cool to see Joan Benoit come back after 25 years and run one quick marathon for anyone let alone a 53 year old woman.)
I think the main difference is the quality of runner is much lower. I'm not talking the top 20, but the mid to back of the pack. I think if you ran a 5h marathon in '84 the finish line would have been packed up and the only people to cheer you on would be your family. Now covering the distance is considered something to be really proud of.
Also, say what you will but America has done a really bad job in the marathon world over the last 25ish years. Only two guys from the US have run faster than Salazar in 28 years. (I don't count Khannouchi as we gave him citizenship hoping he'd run for us in the Olys). So say what you want about all the advancements in training and gear but the reality is in the US it really doesn't matter much.