Many parts don't have colliders with flat faces on 4 sides of the part (cyllinder shaped parts), and it becomes very hard to place a solar panel or anything else perfectly in the center, it always attaches angled and trying to compensate this inclination with little 1° is a very tedious job.

It would be awesome if we had a simple 15° snap mode like in VAB, it would give a much easier and more pleasant way to achieve symmetry.

Positional placement snap would be very useful too, I just made a munar rover in EVA that's pretty much useless due to not being able to get the wheels all exactly the same.

if someone points me to where snap could be implemented I could give it a shot...