For the mainstream home user, maybe true.
I work as a CRM / Business Intelligence consultant (Oracle products). You would be surprised how much work is done in Excel. Macros, pivot tables, exports, large data manipulation, formulas, mass substitutions, etc... Enough to say that one of the most requested features is to be able to export data to Excel for further manipulation.
For me personally buying MS Office did not make sense, I use OpenOffice.org, but I see a lot of my clients use many advanced features. That 'Data' menu is evil
So what you are saying is, the majority of business office users could probably do very well with iWork and there are people with specialities who might need a more complex solution? Like I used JMP (on a Mac!) to analyze consumer survey data because Excel couldn't do what I needed.
BTW- I believe all the things you mentioned are possible in Numbers. Macros would be done through Applescript or Automator.