How many people really use the "serious office suite" features in Office, though?
Most of the users I've encountered just want to add clip art to their PowerPoint. The folks writing an entire application framework in Excel macros are going to keep Excel, sure, but they're pretty rare.
1. Puts data in, and uses little else.
Word is a glorified text editor.
Excel is a table editor with built-in arithmetic.
2. Puts data in, uses slightly more advanced features.
Word documents use some simple styles for consistent formatting. They get spelling checked and word counted. They include the occasional picture, numbered list or table.
Excel spreadsheets use named cells and some basic formatting. They might include a few tabs, perhaps separating multiple input tables and adding some summary tables/charts. Summaries calculate some basic statistics. Charts are formatted to be useful instead of pretty.
3a. Uses "power user" features
Word documents are based on carefully constructed templates with comprehensive sets of styles. Long documents generate tables of contents, indexes and cross-references automatically. Collaborative documents have changes tracked and are passed around for review/annotation.
Excel spreadsheets perform serious calculations, use conditional formatting, etc. They are used to explore scenarios interactively.
3b. Uses automation and integration features
Word documents have custom macros to help when producing specific document types. They might combine data from other sources outside the document into a single place, use mail merge, etc.
Excel spreadsheets have custom macros to handle larger data sets, explore scenarios automatically, etc.
My problem with Google Docs isn't that it doesn't support 3a and 3b, it's that it barely supports level 2. You often can't produce professional-level work with Google Docs, because it lacks even the "slightly more advanced" features, never mind the power user or automation/integration capabilities. And while not everyone is a geek like me who wants to streamline everything and produce perfect results all the time, I can honestly say that in every office I've ever worked in, almost everyone operated on at least level 2.
As much as I appreciate allowing more design features in Docs, I think they should first have addressed the glaring omissions in basic functionality (by which I mean things real spreadsheets did a decade or two ago, not "basic" things that are very important but only to 5% of the market) and the horrible reliability and backward compatibility.