It does seem to be a new trend and I would agree that it's unnecessary with both of your examples but for some reason I've started to want to do this myself, not as in your examples but when launching into a story or an op. No idea why. I do know that it annoys people so resist the temptation but I'd love to say: "So, I was walking along in the park and all of a sudden..."
I don't know if it's recent, but it does feel like it's increased in spoken media in recent years. It can be a bit irritating, although I don't know why. I've tended to notice it when scientists are being interviewed (or anyone else being asked to explain a technical subject). It suggests a kind of "where do I start? So, one way to explain it,..."