Well, there is an advantage to mp3/ogg over midi and vice versa.
Advantages of ogg/mp3
mp3 and ogg will have superior quality about 95% of the time (near lossless format)
Sounds (virtually) the same regardless of sound card, but the speakers do change the sound a lot.
Can produce on all frequencies. This can be good if you want to start from infrasound and build up.
Disadvantages of ogg/mp3
Can be difficult to modify notes individually from a sample
Tempo can be hard to control
Advantages of Midi
Midi is great for using in music programs like Reason where you can place the midi in to tweak all the individual instruments on average
It has a simpler file format thus producing a smaller file
Disadvantages of midi
It can sound differently on different sound cards
Depending on the software, you cannot usually use spiffy sound effects w/o partial format conversion into something native.
Most people don't use midi anymore. A lot of the instruments have usb connections and midi is slower on a computer. I had an old casio that used midi, but I had to get a converter to usb since I didn't have a port for it. There was about a 500ms latency issue so it was slow by about half a second. It took a while but I made it work.
In short, I support Enterbrain's decision.