I thought my question was kind of the same. If there is no advantage of Arch, then it doesn't make sense to use it if it is harder to use. Unless you want to work on improving Arch.
Simplicity of use, packaging, configuration, understanding. No default choices as Unity, it's light and fast, a great distro to learn from, great community and documentation, and much more, that make Arch a great distribution widely used.
Also keep in mind that to a large degree these things are a matter of preference. I like Arch's package manager over Debian's. Things like that have pros and cons, but on some level it breaks down to simple preference.