IT and XM are both Module File formats. MIDI is a very different animal.
IT and XM are just a collection of small sound samples with instructions on what order/pitch/volume etc.... to play them in.
MIDI files are instructions for your MIDI hardware (your soundcard) that tell it what instruments to play (from a set selection) and what effects to apply to them.
Not to say conversion is impossible, but unless the samples in your module files sound like the 128 standard MIDI instruments then why bother?