Not sure I buy this argument. "Clients have to be analyzed for modification" - why? PB works mainly on FPS-style games where you don't want people to run around with auto-aim bots. Does it still matter in Diablo?... maybe to a small extent, but I wouldn't care that much.
"Diablo games are notorious for being hacked" - do you mean server security? This has nothing to do with the client.
"I assure you that if you happen to lose valuable items or characters due to a hack, you will not be happy." - yes, I would not be happy, I would be furious if they allowed it, since it's the server that should control and verify those kinds of issues, not my client. If I don't explicitly allow a transfer, server should deny it. If someone tries to kill me in a way that game-physics disallow, server should deny it.
It's not like you need the official client anyway - the way to interface with the server is already known. There's an unofficial game server available and being developed since late 2011 (http://diablo.incgamers.com/forums/showthread.php?813096-SPO...).
In short - I don't believe disabling the client on one specific platform will help anyone in any way. People can and will write bots that work around such protection. This is more like DRM.