I already have them all, so it's not really that big of an appeal to me. Besides, I still want physical discs for re-installs. Digital downloads of actual expansions would take too long.
I used to like having the discs better, than when I pre-ordered Pets, I must have accidentally clicked digital instead of physical and at first I was upset, than realized I didn't have to wait around for the mail! I just opened my Origin and downloaded it. Than when my sister bought me TLS it was at night and I seriously didn't want to wait a few days for it so I clicked digital and got it instantly. I like it now for the simple reason, if I do have to uninstall and reinstall, I don't have to go around looking for my discs, or worrying if I can't find them. All my sims games are neatly packaged on my Origin.
If I get a new computer, all I have to do is download Origin on that one and sign into my account and they are already on it, just gotta download them. The closer it gets, the more excited I am too, but I can't pre-order it no matter how much I want to. I have to buy my graphic card this month.