Remember, new guns are shipping in a "packing grease" which fights corrosion while the firearms are boxed/stored. You want to get all that stuff off--and it's usually in the bore, too.
Shooting through that gunk can create a high pressure situation as well...bad news.
For those that have cleaned a lot of new rifles, I'm sure we could all tell stories of some of the "gunk" left in the action/bore. I've pulled some pretty sizeable metal shavings in the past--enough that would seriously damage the bore if you didn't clean it before shooting.
Long and short of it--always clean a new firearm, as well as any firearm that is "new to you."
What's 10 minutes?