R/Python/SAS etc. are a much more compelling alternative to Excel than Google Sheets (to say nothing of the actuarial modeling software packages that are used already for more rigorous/complicated problems).
If an insurance company decided to move all of their MS Office users to Google Docs/Sheets etc, my money is on the actuarial department paying for Excel out of their budget without a moment's hesitation.
For keyboard shortcuts, most Excel power users don't use the mouse, so while it sound trivial, it's really hard to feel productive when you have to hunt around for the right button to click.
From an enterprise perspective, Excel is so entrenched it would be a 5-10 year effort to port existing spreadsheets to sheets. Practically speaking, most companies wouldn't see the benefit.
And at the end of the day, it would have worse performance than Excel both in calculation speed and _much_ worse UI. One of the reasons Excel is so much better than Sheets is speed. Insurance companies spend hundreds of thousands of dollars a year on actuaries. Even if Excel cost them $500/year/user, it would be easily worth it for actuarial departments.
The average enterprise network is nothing like as secure as people behave like it is.
Where do you think your email is hosted? With few exceptions I'd expect its provided by a cloud provider these days.