Sometimes I run into problems when I expect too much. This is what I call Crocodile Dundee Syndrome. I call it that because of this friend of mine who went to see it (way back when it was new) and came back raving about how Paul Hogan was a genius and it was the funniest movie he (my friend) had ever seen. Well . . . I went to see Crocodile Dundee, and it was okay, but I think I would have enjoyed it more if I had come in without all the buildup.
Maybe the reason you don't get what the "big deal" with The Stand is, is because there isn't any big deal. It's just a story, not unlike many others. Of course, that's not a perspective you're going to get on this forum (except that you just did), and we all know you can't un-ring a bell, but you're probably not the only person to be disappointed -- not because a particular story isn't all it might be -- but because it couldn't possibly be everything everyone has told you it would be.
Or maybe not.
I dunno.
I get exactly what you're saying. And you may be right. What you call the "Crocodile Dundee Syndrome" (funny!) is what my experience was with the movie "the Exorcist". After decades of hearing it was the scariest movie of all time and being frightened even by the musical score, I finally got up the courage to watch it and...was not impressed. Not even scared (and it doesn't take much to scare me).
I truly enjoyed the beginning of "the Stand" (every time I started it, I couldn't imagine why I had never finished it) until there were more characters than I could keep up with. But my daughter read it and loved it, so I eventually read the entire book.