This is part of a larger trend where programming environments are getting increasingly creaky and complicated. Java started out simple, but it's not anymore. The web started out simple, but it's not anymore. Every so often, development environments need a reboot and I think we're long overdue.
There's also the question of whether all this increasing complexity is actually needed - not everyone needs enterprise solution platforms or scalable web application architecture frameworks. Some people just want to write a few webpages to share information with others, and browsers made it easy to get started. Just because we have some really idiotic users and the page source might contain "exploitable" things like cookie values and session IDs doesn't mean we should remove "View Source" and make it a developer-only option. (If the trend continues, I can actually see this happening in the not-so-distant future...)
There's also the question of whether all this increasing complexity is actually needed - not everyone needs enterprise solution platforms or scalable web application architecture frameworks. Some people just want to write a few webpages to share information with others, and browsers made it easy to get started. Just because we have some really idiotic users and the page source might contain "exploitable" things like cookie values and session IDs doesn't mean we should remove "View Source" and make it a developer-only option. (If the trend continues, I can actually see this happening in the not-so-distant future...)