Well now I'm just mad at Bungie because I can't use my unsupported Halo mods online.
And FYI no you do not need to buy D2 to play over TCP/IP, if you think piracy isn't rampant in the D2 community just lol. You might be the only human being in the scene that's using a legit copy.
Blizzard supports mods in the sense that they let you do it, but they don't offer any support for them beyond that. If you want to keep playing your modded game by all means keep using your classic client. If you want to play the official D2 game with updated graphics and such buy D2R. Again, total nonissue. You're just being outraged for the sake of it. You can keep on doing exactly what you're doing.