I don't use XAMPP never liked it. Personally using AMPPS at the moment since leaving MAMP because development was lacking for awhile ( http://ampps.com/ ). But the websharing is a built-in feature of OSX in the System Preferences. If you are using a 3rd party app it should not be affected.
Starting Apache is very easy. Simply type the following into a terminal:
sudo apachectl start
I think that they removed the tick box because it's so easy to do from terminal, and not something that most OSX users need.
As SnakEyez02 mentioned, using a package like MAMP or XAMPP doesn't require this. Those apps run their own Apache