People ‘choose’ where they put their faith....be it in something they 'believe' has power... they ‘touch’ or what they ‘see’....in order to create an anticipated experience by such an attachment,... or something more than the sufficiency of Jesus Christ and what he has accomplished...... Yet Jesus said “Blessed” are those who believe without seeing. .and that our faith is increased in this manner ...”Faith comes by hearing and hearing the word of God”.....
Relic worship/venerating isn't necessary....in fact as you said, with dismembered body parts, it certainly can be seen as ‘revolting’......and I'll add health risks. For the Christian faith I practice to even think there is power in dismembered body parts is like believing ‘in channeling’... practiced by soothsayers/magicians and their lot.
Not a single Catholic, qua Catholic, venerates the dead. All of the saints are alive in Christ, they have survived as St. Augustine puts it, the second death. Catholics are forbidden from praying to deceased relatives and friends since they may not be in heaven. But canonized saints are in the glory of the beautific vision, wrapt in the unimaginable Love of God. Any Grace we receive through their intercession comes from Jesus Christ. The Communion of Saints is a lovely thing. We get to participate in God’s gift giving. Much like human parents get to participate in bringing a new person into being and into eternity from nothing.
The miracles associated with holy relics, whether it be things associated with saints such as clothing or articles or bits of their bodies is undeniable, often unexpected. If one’s reality involves denying this reality, what type of reality is it? There is also the problem of incorruptibles. Why does God preserve some of his saints bodies incorrupt? Why is St. Jacinta incorrupt? Why is St. Rita de Cassius incorrupt? Why was the heart of St. Joan of Arc found incorrupt in the ashes? Or the tongue of St. Edward the Confessor only? What is God trying to tell us? One can deny such things, but they do exist, and such denial is again someone’s safe little reality that is not real.