The priest doesn't get to select the instruments of the Holy Sacrifice of the Mass according to his own personal feelings. He has a job to do and he has a GIRM to tell him how to do it properly.
God does care if people obey the Church he established on Peter or if they disobey it. He cares a lot.
You know I agree with you 100% here on dogmatic (faith and morals) issues and even matters of discipline. Took me a number of years to understand, but I'm there, by the grace of God.
However, reading the GIRM on what constitutes proper make up of the chalice... it's all over the place. I know what I would use (precious metal) and why, but it seems that when all is said and done, precious metal is a strong suggestion in the GIRM and not liturgical law. Way too "all over the place" - just like Tabernacle placement.
Drives me nuts.