Skip these unless you like "stupid comedy", then these might be worth the 30 mins. Also if you consider these as a standalone short series rather than related to Accel World.
Chibi artwork is cute but this adds no value and has maybe 1 or 2 slightly funny scenes briefly. It is more what I would call "stupid comedy" that might be funny because it is so stupid and the character personalities so wacky and different from their originals that it would be considered ridiculous in the first place. This has no connection beyond the chibi versions of the main characters and delivers very little enjoyment when you think about what Accel World is.