The single best selling point of Teams is that it's included in the O365 subscription every corporation has anyway so that they can get Powerpoint, Excel and Word
I'm not aware of a report that shows "popularity of Excel", but I can give some points.
* I pay for my own Excel license because it's so useful for me in a variety of contexts. My wife does all our family accounts using it.
* Globally, Microsoft estimate 1 billion monthly active Excel users, and said at a conference last year that some admin staff spend approximately 30% of the week using Excel.
* Training for Excel is a top selling course on Udemy.
* Working in Enterprise, there were a lot of people (BAs, Finance, PMs) who said they would quit if IT didn't provide Excel.
So I'd say "yes, there's a lot of people who want Excel".
I'm sure there is less enthusiasm for Outlook, but amongst people who live in calendars and email, it seems to be pretty popular.
I’m surprised they’re taking this direction, given that no one I know of likes Teams.