You are right that there are lots of better tools for tasks users use excel for, but 2 which spring to mind for me that devs haven't paid attention to are form/table design and databases:
Form design: It used to (ok, still does) drive me crazy when I see excel used to make flyers and forms to be printed out. But for the users what could be easier than drawing a box on the screen, adding a line weight, and then drawing other boxes inside that using the convenient spreadsheet grid? Why hasn't someone designed an app that works that simply?
Databases in excel are another monstrosity, but for a lot of users, all they want is a simple lay of listing things which they can then sort, and maybe sum a few totals on. Firing up a complete RDBMS is over kill for this use case.
So I see the biggest problem with spreadsheets as why aren't we learning from the way people use them and putting this into action?
No, what I am terming "poor IT policies and organizational practices" is people being restricted as to what tools they are permitted to use in a blanket way that doesn't consider task specific needs, and having imposed difficult, inefficient, bureaucratic processes to get either permission to use other tools or support from the people that are permitted to use other tools, and/or which result in poor quality of support when those authorized to other tools do end up supporting them (often, again, because of inefficient, bureaucratic processes.)
You can disagree with my perception that this one of the biggest problems with spreadsheets, but please don't try to redefine what I'm actually talking about.