Oh it's just a bit of fun, if you don't like it just ignore it along with the other announcements. I don't mind someone showing a bit of character.
Years ago I was on a XC 125 when the buffet car attendant came on to advertise his offerings. This chap was extremely camp, and started telling us about the sausage bap "oooh, I love a good sausage, don't you?" etc. whole train was in stitches and he did drum up plenty of custom.
And it can also help keep things calm. Not long ago I was on a late night delayed EMR out of St Pancras, it was absolutely rammed due to previous cancellations, and one coach was boiling hot due to broken AC. The guard was absolutely brilliant, went way off piste on the announcements, not being funny, but just not reading any sort of script. Apologised for the conditions, kept everyone informed when and where seats became available, carried several crates of water to the people stewing in the hot coach.
Can't have it both ways, if you tell people to stick rigidly to a script that's what they will do.