Finance guy here (hobbist programmer). The more I think about this, the more I realize the way to exploit this is through well designed and _specialized_ software which doesn't have to evolve around spreadsheet at all. You have to look at the work flow of the professionals using (abusin) Excel.
I give you an example: audit. Now, the final product of an audit review is what? An MS Word report, that's what they sell the client. How efficient is this? Barely efficient, consider that:
1. There is no version control.
2. Tables and pictures look horrible and are a pain in the ass to format (oh latex)
3. The doc is edited by various people: people paste in the report the wrong stuff --> client gets crappy drafted doc --> bad image
4. The document "links" to different workpapers (Excel sheets with the calculations) that you have to go and pick up, you can't click and get the doc like it was 2013, you need to search it like in the 80's
5. The senior has to review it all, guess how easy it is to do this navigating tons of MS docs and spreadsheets
Then you get to the spreadsheets... it's another mess:
1. No audit trail
2. No workflow of how you go from the original data to the calculation. This is very important, you need to tie to the original source of data ALWAYS
3. You use crappy templates 10 years old with things nobody knows anymore
4. You can't read well .txt files and you can't process big amounts of data (what if you want to test for frauds in petty cash in a 20 billion multinational? For example)
I mean, there are tons of inefficiencies, the points are 2:
1. How you sell your shiny new perfect product to people used to abuse data in this way?
2. How do you build such a product from a programmer background? And here I have my rant about ideas not being useful, they are if they come with lots of market insight focus.
And that's about it. I think, coming to your point: yes, there are inefficiencies, no, you will not get there if you don't have insight into the specific profession you are trying to provide tools to.
So how come users still manually set the font size for their headings instead of using styles; how come they ignore Track Changes; why do they copy spreadsheets instead of enable the Share Worksheets functionality -- and so on -- well, it's simple: they don't know about them. Most Excel/Word users are self taught or are given a very rudimentary training course by their peers or one of those cash-generating "Certificate Farms" you pay out the nose for.
I definitely agree that to solve the Excel woes you're going to have to write domain-specific software; Excel's already the Swiss army knife.