Will there be consequences or issues if I install XQuartz?
It's absolutely fine, it's essentially a standalone application that you can uninstall again anytime. Except when you're running Inkscape, you'll never know it's there.

In fact, XQuartz used to come on the OS X install DVD (though it wasn't installed by default), but like Java and Flash, Apple just prefer not to package and ship those things with the OS any more, and require you to install it separately direct from the developer.

If you're still not sure, there is a native port of Inkscape in progress that doesn't require XQuartz, but it was a little buggy last time I tried.