Why all the excitement? Three things.
One, battery technology and device efficiency have gotten to the point where rich media on portable devices doesn't drain the power before you're done thinking, "Hey, I'd like to experience some rich media content right now?"
Two: The lines between every traditional computer category are collapsing all around us. Your phone is a slim client, your ebook reader is a netbook, your htpc is a nettop, your desktop is always connected and serving up content, up is down, down is left, cats and dogs are living together! And all this requires that we think a little differently about how we handle, view, sort, and access our delicious data.
And Three: Ohhhh how much data we have! And it's cheap to store. And for the price of a 14" CRT in 1993, you can grab a high def 60" mega-monitor (okay, you'd have to get it second hand and last year's model, but still...) In other words, we have more sand and bigger sandbox to play in.