Earlier quoted context omitted.
The difference: when you use a Mac, you don't need that software. - You don't need to run third party antivirus or antispyware software on the client, only on your mail server (to protect Windows users if you forward Windows executables). OS X has built-in malware protection. - You don't need third party management software, you can use NetInstall/NetBoot or ARD. - Using NetBoot also solves the backup problem on the…
I'm also pretty sure that once MacOS starts becoming prevalent in the enterprise, they'll eventually need antivirus, back up agents, and some sort of management agent as well. How would an IT organization manage the settings on the OS without some sort of management agent?
There are already IT management tools for Macs. I've worked at two large companies in a row (25k+ employees) where a large percentage of the company was using Macs (~30% or more) and they both had established management solutions that didn't bork the user experience on Macs. I'm typing this on a managed Macbook Air right now.
As for backups, those agents exist but they're rapidly growing less relevant as the majority of documents and work are either web-based or on servers anyway. If I somehow lost this computer, I'd be bummed to have to do some preferences setup again, but I wouldn't lose any work.