I guess the problem to consider is what happens to continuity in cutscenes. A lot of time you will be chatting to an NPC under your umbrella - then a cut scene plays so you can nod - the umbrella won't be there - and then you come back to talk and you are holding an umbrella again.

They can't have these things happening in cutscenes as - taking a mount for example - how does your character do 90% of the animations they make us do as you are sitting in your car, or on your whale, or sabotender?

So, rather than that continuity break from dialogue to cutscene I imagine they thought it easier to put the umbrella/mount away.