Your review of Google Presentations (I've never in my life heard the word "preso" and I don't intend to start using it) is spot on - it's a nifty slideshow designer that has its primary strength in collaboration, not presentation.
It can't even come close to what veteran presenters need to do on Powerpoint. Its collaboration strengths, on the other hand are unparalleled in the Microsoft world.
But it boggles my mind that you think Google Docs and Spreadsheets don't have the same weaknesses. Excel is so powerful, more so that PowerPoint, that using Google Spreadsheets just doesn't work as a substitute. Sure, it will work to keep the neighborhood phone directory online. But if you're looking to do financial or statistical analysis, forget it.
These three are supplements to Office, not replacements for it. And if Google doesn't provide some real upgrades to its office software, you can bet that Microsoft will roll out its own collaboration tools that will make Google irrelevant. Why use a watered down Google version of Excel when you can collaborate with the full-powered real thing?
Free? Sure, but no business is going to kneecap its professionals with Google.