Sounds like people are mad about this! It sounds like if you have someone over at your house you will not be able to make a direct local connection with them, despite the fact that it was a promised feature earlier this year:
"You can still connect locally through TCP IP if you want to!" Fergusson said. "That was there in D2. It'll be there in D2R. We've really focused on making sure that if there's something about the core experience you loved, we're bringing that over. But we do get a lot of benefits from being on a more secure platform."
Just browsing around it sure seems like people are pissed about this, but I have to imagine that's more just because of a broken promise than actual functionality being lost. I can't imagine there will be a ton of LAN parties without an external connection to Battle.net to set up private lobbies, but still - it's a feature that was being promised and has now been removed, which is bad. And I can't really buy their explanation of it as a "security risk" aside from maybe allowing some hacking/modding, but I'm no network engineer.
The more I think about Diablo II the less I think I'm super interested in playing a remaster of it? It's one of my all-time favorite games but I think replaying it would either leave me doing Meph runs all night again or just sully some perfectly fine memories of the summer I lost to the game. But we'll find out soon, I guess.