One of my peeves is the use of "in my opinion ..." since pretty much anything anyone says is, by definition, their opinion.
Yet your mention of the phatic (thanks, too, from teaching me a new term) is interesting. Those little qualifiers, even when not strictly needed, do seem to keep the wolves at bay.
But that doesn't at all mean that it should play the same role in writing.
You say phatic language is about maintaining the connection. If I understand this correctly then there's a role for it also with people one does know well. If you prefer referential conversation and meet someone who's completely restricted to that part of language, you may initially enjoy the conversations a lot. But, after some time (this could be months or years), despite their referential content they may appear increasingly "empty": you realise you're still completely replaceable as a conversation partner by a random new person.
The bit about using phatic language mostly with people one doesn't know well is not from Jakobson. I made it up, and it's probably wrong. I didn't go over that sentence 20-50 times :).
But as there are four other components according to Jakobson, I should be careful. Added Jakobson to my reading list.