I will note however that they didn't say anywhere on their site "the only player that will play ogg files is VLC" but rather "there are many players that will play ogg files, the one we like is VLC".
Ah no; they say
To access streaming Ogg files you need a media player that understands the Ogg Vorbis format. Many different free software players work with Ogg.
Note the clause "many different free software players". Now consider how gnu redefined "free" to mean what that wanted it to me; gpl code.
Again it's simply unrealistic to push VLC onto iTunes users. If they wanted to truely push Vorbis they'd have offered more instructions for other players, or at least pointed out that it will work in iTunes and WMP and here's the links.