I spend around 50 hours in the air every month; yes, a full working week. I rarely have - or want - Internet access on those trips.
You are an exception. Very, very few coders travel by plane that much.
Git (and most other DVCSes) allows me to work revisioned, trying our various paths of development, during that working week.
Local work is not a unique property of DVCSes. (See shelving / checkpointing planned features in SVN 1.8).
Related, I like to test branches and ideas without having anyone else observing my moves or caring about what I do; so, I can do that, locally, instead of creating obscure or sacred branches in SVN in a common repository.
This is a very good point. Though it is still a specific need. The VCS is here to help the team. If individuals want to play on their own, it's only "nice to have" IMHO and shouldn't make the other part of the process more complex.
There are a bunch of more technical reasons why Git is superior to SVN, related to the snapshot representation of files and trees of files, and commits, instead of deltas (such as in SVN.) If a delta chain (or poset...) gets out of sync, you are kind of lost; very hard to recreate the current (or any) consistent state of files.
One could argue that it takes a bug in SVN to get stuff out of sync while it only requires a user error in git, but yes that's a valid argument. Not as strong as you say because whether you have a SVN or git repos it would be very stupid not to have automatic backups for it. I'd be happy to see more details on that point. Julien