If you just choose to use your attic space for storage, it will still require maintenance, just as every other part of your home does.
The attic door being properly insulated, no matter which version you choose, is just one of the things you take care of when you have an attic.
You need to check your vents and fans in our attic every year to make sure they aren't blocked and gathering debris. You also need to check the insulation in the entire attic to see if it has moved and created gaps over time. This should be done once every 5 years.
Lastly, the attic should be checked for any cracks that can let critters in, or leaks that can damage your home.