I think the announcements at the Conventions and Assemblies is more about adding weight to the words the guy is going to say, and not an ego thing. (By the way its in the instructions for the talks and for the chairman)
The convention programmes used to be printed for each location individually and included the names of the speakers (and congregation?) next to their item/talk - that stopped a number of years ago and just a generic programme is printed nowadays.
The announcing of the name along with their congregation name or circuit (if a Circuit Overseer) or if they're in Bethel etc is fine - it's when they start saying how many years they've served doing this and so many years doing that when it grates.
But it depends how it's done, occassional exceptions could be made, perhaps for 'human interest' reasons - maybe adding they used to be a missionary in such-and-such country if it was fairly unique, or perhaps knowledging the brother's personal situation that would add weight to his talk.
Otherwise it just sounds like a competition - which speaker has done the 'most' and the 'longest' whatever