That's the main issue we're facing with the new Concordance, and I answer it thusly: It's a lot easier to browse through a physical book than a website.
Memory Alpha is a fine site (and we're pulling a lot of tidbits to fill gaps from there), but it works best if you know what you're looking for. If you just want to wander around and stumble across stuff, not so well. THAT is the advantage that physical reference books will always have over electronic media, and why there will always be a market for them.
I'm not sure what you mean. What's the difference between flipping open to a random page in a book, and clicking the "Random Page" button on Memory Alpha?