Back in the day, it was a great product. My family had an edition endorsed (in the first pages) by Queen Elizabeth II and Richard Nixon, and I can't calculate how many hours I spent leafing through the pages. I guess that's been replaced by Wikipedia's "Random article" link, but with EB you never got crap about Pokemon.
There was huge value in thumbing through these as a child. We could never afford the set, but I had used copies of individual volumes and I spent many, many hours reading random topics. You just don't get that kind of discovery in an online version. Maybe you could, but you don't.
Seriously? YOU don't? You've obviously never experienced the Wikipedia death spiral: 30 browser tabs open all on unrelated Wikipedia pages. It was dangerously close to an addiction for me at one point and the amount of random crap I now know it irritates me I'm still so poor at pub quizes. There's probably some Godwin's Law equivalent where once you've opened a tab relating to Hitler or the Nazis, having started off on an article about Bengal Tigers, you know it's time for bed.
The problem is that you're selecting the topics. The value of a physical encyclopedia is that they've selected the topics and you're browsing them at random.
I agree - I have a lot of nostalgia over this, as we had a complete set of the 1921 edition - reading though that to see just how much the world had changed (and this would have been in the 80's) was fascinating.