Arc is an indomitable name. It's short, memorable, recognizable, and pronounceable. It's also a strong prefix: Arc app, Arc box, Arc sync, Arc OS, etc.
Arc passes the highway test with flying colors. Imagine driving down the highway when an 18-wheeler thunders past. If you remember the name stamped on the side of the corrugated shipping crate, it's a good name. 'Arc' in a Neo-grotesque typeface next to an iconic logo on such a shipping crate is as good as burning Arc into your retina with a megawatt laser.
You've evaded the GP's comment, which is about the name "Arc"'s rather obvious existing binding. Why? I'm curious to hear by what process you've decided to ignore that.
At this point the name is so overloaded, I suppose we could criticize most post-'80s things named "Arc" on that grounds. I haven't heard pg/rtm defend why the Arc programming language chose to clobber the existing extension .arc, which is widely used by the ARC archive format. Or the binary 'arc', which has been used for ~30 years as the name for the command-line interface to the industry-standard ArcGIS. There's also a programming language in ArcGIS named the Arc Macro Language.
Those are good points. I suppose the counterargument is that it depends on how much the contexts intersect. It seems to me that in this case the contexts intersect rather a lot. But if I'm wrong, and overloaded project names don't matter, so much the better.
Arc passes the highway test with flying colors. Imagine driving down the highway when an 18-wheeler thunders past. If you remember the name stamped on the side of the corrugated shipping crate, it's a good name. 'Arc' in a Neo-grotesque typeface next to an iconic logo on such a shipping crate is as good as burning Arc into your retina with a megawatt laser.