The thing is, pretty soon, the only machines around will, for the most part, be machines with light-speed CPUs. At that point, it will very much cease to matter how "bloated" an app is. If it's fast, it's fast.
Now, not that I'm promoting Office. I do use it, I have to for my job, and XP is an improvement in many ways (and a step back in many others), but I'm just excited to see how quickly StarOffice etc. will leap on the file format and undercut Microsoft big-time.