Taking the first steps on the road to enlightenment does not mean that one will complete the journey. Zen koans lead one to wisdom, but can be frustrating and puzzling to begin with.
Jesus must have been thrilling and charismatic, but as another comment notes, it is an easier sell to push heavenly rewards. And a better business model, as the priesthood enjoys the benefits without having to provide the rewards.
Thomas may be integrated into the canonical gospels - and indeed is pretty much already there, though some of my favourite verses didn't survive - but the reverse is not true.
Wisdom comes from within; it cannot be poured into the ear of the listener. Jesus is, in Thomas, shining the light. Follow the light, follow the logos.