The problem with XAMPP/lampp is that the 'installlers' (in the case of Centos [RHEL based] - usually 'yum' - 'apt' for Debian based distros) for Linux distributions are unaware that lampp is installed. Remember, all you do is copy the files into /opt/lampp, there is no installation really. http://en.wikipedia.org/wiki/RPM_Package_Manager
Normally to update one 'piece' of a traditional LAMP stack you would find a repository that had the component you needed (in the case of Centos - a .rpm file). This file knows all the individual components that are needed to upgrade (dependencies) and where to look for them. The installer file knows where to look for them because starting from when the distribution version was put together, everything that has been installed has been put in the standard location (filesystem path) for that Linux distribution. So, if you wanted to upgrade PHP, it would look in the database of installed files and libraries and determine what needed to be added/updated to make the new PHP version work.
Now comes the problem - the installer doesn't know where to find 'lampp' or its parts. Some minor things can be fixed (compiling a single library or .SO [Shared Object] -- although they would need to be 'transplanted') or updating phpMyAdmin (which is relatively independent of xampp), but Apache, PHP and MySQL may need to be re-compiled. That is nearly impossible, as you don't have all the information needed as to the state of the system as a whole.
The very most basic problem is that XAMPP/lampp is a silent installation that puts all of its components into non-standard locations. That is the downside, the upside is you can instantly start work, you don't have to run all the installs/upgrades - because all of XAMPP's dependencies have been resolved in the package - look in the opt/lampp folders - everything needed is there.
The short analysis is - if you need to change components at will, you should always use an installer based LAMP stack, if you need a quick installation for testing and development with a single stable environment made of the same, matched 'pieces' - XAMPP/lampp is a good solution.