Tying dialogues to Short Rest is mechanicaly impossible ... i thought we are allready beyond that, since it was repeated at least dozen times. O_o
No. This is nowhere near mechanically impossible and repetition wont make that claim any more true. There are many implementations that would enable this: short rests taking place at base camp, dialogues during short rests taking place at base camp, dialogues during short rests happening in the main world, dialogues during short rests happening in their own short rest pocket dimension, etc. Each solution would require some amount of work from Larian, but work does not equate to impossibility.
Also, the goal is to *untie* dialogues from anything. You should be able to talk to your companions nearly everywhere, without having to commit to take a long or a short rest.
Shoot. Untying dialogue from all rests would be most ideal, but that is only true for dialogues that make sense. I mean, SH saying, "I'm not sure this is a good idea," only makes sense when you rest at the very beginning when you believe you're going to turn into a mind flayer minion in hours after infection. Gale's Mirror Image dialogue also only really makes sense after hours of adventure have gone by.
Some, however, don't need to be tied to any rest.
Anyway, at least tying those rest dialogues to both long and short would ensure players experience them as opposed to just LR. Gale's Mirror Image dialogue doesn't really make sense after you meet Nettie, so having dialogue triggered by all rests would more likely trigger this before then - and the Go To Hell one too.