I can't imagine living without that feature, but I also do a lot of OSS work so I'm probably biased.
And if you and another developer make conflicting changes while offline? What should happen when you return online?
E.g. with current svn you get the latest changes from the server, open a diff editor, fix the conflicts and then commit.
The only difference here between svn and git is that svn merges the 'commit' and 'push' operations into one, e.g. instead of not being allowed to push, you're not allowed to commit in svn if there are pending conflicts.
This would be the part that would need to change if svn would get a proper 'offline mode', e.g. commits would need to go into some sort of 'local staging queue' until you get internet access back, and conflict resolutions would need to happen on the commits in that staging queue. But I really doubt if that's worth the hassle because how often are you actually without internet while coding?
Also, designing around distribution meant that merges have to be fast and work well -- this is a problem that most centralised systems struggle with because it's not a key part of the workflow. Branching and merging are indispensable tools in version control and I'm shocked how long CVS and SVN survived despite having completely broken systems for one or both. Being able to do both (and do stuff like blames over the entire history) without needing to communicate with a server is something that changes the way you work.
My actual hot take (as a kernel developer) is that email patches are good, actually. I really wish more people were aware of how incredibly powerful they are -- I have yet to see a source forge that can get close to the resiliency and flexibility of email (though SourceHut gets very close). git-send-email has its quirks, but b4 honestly makes it incredibly easy.
(There's also the owning your own data benefits that I think often go overlooked -- reflog and local clones mean that you cannot practically lose data even if the server goes away or you get blocked. I suspect Russian or Iranian developers losing access to their full repo history because of US sanctions wouldn't share your views on centralised services.)
