After checking this thread, I downloaded Libre on Windows and played around with it a little, to refresh my memory. My main use case is just working with some personal spreadsheets in Calc, no complicated work stuff.
I wouldn't say features are missing, if anything it sounds like Libre is way more fleshed out than OpenOffice. That said, I still prefer the (relatively) legacy UI in Open Calc than the slightly more modern UI in Libre Calc, just a personal preference. It doesn't seem that much more advanced, and after all these years an ODS spreadsheet still looks like a spreadsheet. Other people noted the security posture of Libre though, which is a great point.
Just wanted to chime in that your reasoning here is 100% valid.
I'd also be curious about something: suppose you used LibreOffice for a week or so for working on your personal spreadsheets. What percentage of your work time would you waste either searching for the new location for the old command, or learning the new command that maps to the old one?
I'd love to read a case study where someone has documented this with a UI change in FOSS.
For me personally? 0%. I just do simple copy/paste, scatter plot, sort asc/desc... not a heavy user of hotkeys. I had some trouble finding the Chart button at first since the icon's different, but that was the only issue.
I wouldn't say features are missing, if anything it sounds like Libre is way more fleshed out than OpenOffice. That said, I still prefer the (relatively) legacy UI in Open Calc than the slightly more modern UI in Libre Calc, just a personal preference. It doesn't seem that much more advanced, and after all these years an ODS spreadsheet still looks like a spreadsheet. Other people noted the security posture of Libre though, which is a great point.