View-source and inspection techniques are probably the most important feature set for the open web. It is creativity lubricant, and helps aspiring web authors learn new tricks. I strongly believe that this is one of the main forces driving rapid innovation on the web. What other platform is so open that you can just pop the hood and take a peek? Yeah yeah, cars have hoods, you can pop them and peek, I know; to make a car you need lots of fabrication equipment or at least parts and an engine hoist, but to make a web site you just need a computer and vi.
Software is a magnificent, intangible product that is completely the result of imagination at work. One could liken it to art: software is a clever rearrangement of bits of digital data whereas art is a clever rearrangement of "bits" of color and texture. When we can inspect how the artist creates, we learn new tricks that evolve our own web-art. A web without inspection tools is like viewing low-resolution copies of famous paintings; the artists' brush strokes and exact color choices aren't present, so hints to any method is gone and you only see the end image. I can't grow my skill as an artist by knowing what other artists paint, but I can learn an awful lot by seeing their brush strokes up close.
When I asked him what he thinks is the best part of the web, Cory Doctorow said "view source." He spends lots of time thinking about technology with respect to its benefits and drawbacks, so I give much credence to his opinion. Inspection is also how I learned to make my bits of the web, so I am a bit partial.