Every square inch of your home is an area for home owners to understand and get into. We own it, we can use it.
I understand that certain areas should not be used for storage. Like you said, leave it without a floor and people won't use it.
But every homeowner should understand their attic and crawlspace, and dare I say, check them out from time to time. Or hire someone to do so. It is very important to keep a watch on the attic for slow building problems such as small leaks, bee or bat infestations, etc. The easier access, the better.
Your builder -- like mine -- may not have had a good place to put it that works with the ceiling joist/truss and utility layout. We created even less options after installing HVAC.