To me It holds the same nostalgic appeal as the comic books I collect - for that reason I need to buy one every year regardless of how relevant it remains
I picked up my first overstreet in 1989 - it was the single most exciting experience in my newly found love for collecting vintage comics as a kid. - you had price guides, articles, market information, vast comic book historic information, educational tools on grading, nationwide dealers selling rare comics I could only dream of owning one day, and detailed info on 1st appearances, key books. Reading overstreet taught me amazing fantasy 15, not amazing Spider-Man 1 was spideys 1st appearance. It taught me that many other characters like Thor ironman Batman Superman Wonder Woman green lantern etc 1st appeared in other titles and not their self titled issues which blew my mind at the time. In short it has every aspect of the hobby contained into one source
for me the simple answer to your question is that overstreet is a true comic book institution that must be supported and kept alive for future generations to enjoy and discover - regardless of the fact that it might not be as relevant as it once was.