The fact of the matter is that many people are scandalized when a priest “drops out”. Part of it may be that people naturally expect someone to keep their promises; and the promises of the priest are certainly solemn ones. In addition, the priest is the spiritual leader, and it is seen as a spiritual abnegation and abdication of that leadership. Priests, of all people, because of the postion they have of spiritual leadership, are exepcted to lead, and part of that leading is living out the vows and promises they have made. Leaving is seen as abandoning all of them - the promisies, the vows, and the people.
As to the rules laicized priests have to follow, they have had a position of spiritual leadership; if they have given it up, then they need to give it all up. Too many of them want to keep their “oar in the water”. Well, if they do, then they should stay priests; if they don’t want to, then they should stop trying to have it both ways - not being a priest, but still teaching and leading spiritually. It may be crude to say “fish or cut bait”, but that goes to the essence of it. Further, it can cause untold confusion if one were known to be a priest, laicised, and seen as perforimg functions that often (although not necessarily) are done by a priest.
As to the pomp - or rather, the quiet marriage; the priest had made a vow/promise of celibacy; he hs been relieved of it, but that is seen as something somewhat at odds with marriage.