Okay, I should've been more specific.
Yes, duct tape will probably pull paint down or leave residue when you
take it off, and it'd have to be reapplied every time you go into the
attic (so maybe there's better tape to use that's less sticky).
But that's IF you go into the attic. Some people go there a lot, some
people go there twice a year (storing clothing, or window screens, so
it's seasonal) and some people rarely go there.
Closing off an air gap will make much more difference than adding
insulation where there's no gap but, say, only a wood barrier.
Compare, for example, a window vs. a slightly open window- which do
you think is worse for losing heat?
If you can put weatherstripping all around wherever there's a seal
when you close it up, and you can get a perfect seal, that's great.
Most attic pulldowns I've seen (and no, I haven't seen all that many)
eventually warp or bend or something so parts don't meet exactly flat.
Just by way of example, I resealed the weatherstripping on my front
door last week. I had to use a couple of different widths of
weatherstripping because the parts that met weren't perfectly plumb.
And those are vertical parts where gravity's not an issue, vs. pull-
down steps that may not hit the ceiling exactly right when they're
pulled up by a spring on one side. The only weight on my front door's
hinges is the door whereas the weight on my attic step hinges includes
part of my body weight when I climb upstairs (yes, most is on the
floor, but not all of it).