I think the answer is simple… it is simply not a tradition for many of the Eastern Catholic rites as it is not a practice for the vast majority of Latin Rite Catholics.
Why? My guess for both is that, considering it is a relatively new practice, most Catholics prefer a more traditional devotion / approach to the Eucharist. That is to say an intra-liturgical interaction versus extra-liturgical.
It is a devotion that is approved, if not encouraged by many in the Church’s hierarchy, but certainly not something that all Catholics are called to. One can be a perfectly good Catholic and never go Eucharistic Adoration.