It's Outlook with Exchange that is the clincher. Even if OOO came up with an Outlook alternative, wouldn't there be licensing issues with connecting to Exchange unless you wanted to use pop3 or something.
The only way I can see this happening is if OOO start doing an Exchange alternative as well, because lets face it, Exchange is how hugely bloated as well. If there was a free to use email client & server solution that was actually any good, I'd jump at the chance to implement it.
Maybe there already is, anyone know of one?