Yes, it's the shoes, and the tracks, and wavelight, and the Internet sharing of knowledge, GPS watches, Instagram and social media giving a bit of glamor to teenage runners, YouTube enabling kids to be inspired by past greats etc etc
There have probably been more changes in the last 20 years than the previous 100 years. Then look at how times improved over the 20th century, and people here are screaming doping because a rarely run 30 year old record has been broken by arguably the most prodigious talent of the last 100 years.
The crazy thing is how it's taken all these changes and yet the men's 1500 and mile record still look secure for the time being. Surprised El G is still alive with everything that must have been put in his body to run 3:26.00 30 years ago.