The number of slashes one must use in Vim regexes is very, very unfortunate:
:%s/\(\w\+\)\(.*\s\+\)\(\w\+\)$/\3\2\1/
Is there any way to reverse the rules so that I can write
:%s/(\w+)(.*\s+)(\w+)$/\3\2\1/
And I would only have to quote (, ), ., *, +, etc. if I want them to match that literal character?
What you refer to is called "very magic" mode (see :help magic).
You can switch it on for an expression with the \v flag:
:%s/\v(\w+)(.*\s+)(\w+)$/\3\2\1/
By default this is not enabled and it's not a good idea at all to enable it by default. But you can always use it in a per-expression manner.
There are two different magic modes, switched on by \v and \m, and switched off by \V, \M respectively. Just like case-sensitivity via \c and \C, you can use those flags to make only a part of the expression magic.
But if you switch it on at the start of the expression and don't switch it off again, the entire expression is seen as magic.