If you don't know yet reasons to keep them separate, please google about it before arguing without arguments. For example, read about Separation of Concerns: http://en.wikipedia.org/wiki/Separation_of_concerns
Separation of concerns and separation of technologies are a different thing. It would appear you haven't done your research. See Pete Hunt's famous talk:
Hm.. I didn't say a word about separation of technologies. If you have one non-broken piece of HTML and related piece of JS to make it "live" - it's one thing. If you use JS/php/python/ruby/lua/whatever to generate HTML, composing it by small pieces into one (inside one component) - it's another thing and it's exactly what I'm talking about.
You are just throwing unrelated links around. Parent's point was that in this case, logic and representation are one and the same concern. What you're doing is similar to using SoC to defend having to split up class definitions into .h and .cpp files.
Don't put your words into my mouth with "allegories", I hate it.
I don't talk about cpp and headers at all, I talk about view templates and view logic.
//You can use "they" to replace "he/she".