Yeah, I mean more as a GUI enhancement. It might be outside the scope of Jupyter, but I think it'd be neat to be able to treat DataFrames like a spreadsheet.
Personally, I'm comfortable writing Python, but I bet you'd see more adoption for non-programmer academics who still need to work with data.
I'm of the same mind about Excel, which is why I don't use it any more. I don't like anything where there are hidden layers of meaning that are easy to overlook. I like Jupyter because everything is right there in front of you.
Another shortcoming of spreadsheets is that they don't solve what I consider to be the Fundamental Problem of Programming: How to keep your sanity when your project gets bigger than one screen or one page. Of course programmers have lots of ways to deal with this, by creating named abstractions, subroutines, and so forth. It's why we can write million line programs today. But how it's solved in Excel seems incredibly clumsy by comparison. Of course you can adopt the conventions of programming by using Visual Basic, but that seems to occur quite rarely.
I use Jupyter as a lab notebook, and it's OK to enter data by hand in an array literal, paste it from a spreadsheet (it comes in as tab delimited text, which is easy to mung) or read it from a text file.
But an edit-able tabular data array (that was also accessible programmatically) would be really super.
Personally, I'm comfortable writing Python, but I bet you'd see more adoption for non-programmer academics who still need to work with data.