Should the utility room be left unplastered?

I can only agree: an unplastered room, even if it is just the utility room, gives an unfinished, uncomfortable feeling. Our site manager recommended that we paint the utility room before the screed, because it is more difficult after the installation of the appliances. However, the painters are not booked until August. Since we are rather inexperienced in craftsmanship (especially me), our site manager showed us how to fill joints, and this weekend we want to finish. There are also many YouTube videos on the subject, and since the utility room does not have to be perfect, I think this is a good solution.

The question is first of all: What advantage do you hope to gain from it?