Because in many configurations I have hosts that cannot go online. XenServer includes multipath-tools so I can configure it out-of-the-box. At this moment I'm testing PVE and oVirt to find a XenServer alternative. Thank you for the fast reply.
It would be great if you could remaster your own ISO to add things like this. I can relate to @Frank_Pit, I also have to install it often and if you do not have any internet connection, it can be a PITA.