It depends on what you're trying to do with these bees. The bees naturally live in the wild, so having a bunch of holes is perfectly fine to let them do their thing.
If you are raising
cattle, do you let your cows roam in the fields with no fencing, no caring if they're sick, or provide no support? The same occurs with bees IF you're trying to manage them for a function.
To increase their numbers, a bit of management is important. Pest control is important. You can do this through harvesting in January.
If you're raising the bee where it naturally lives, then keep it outside. If you're managing it where it doesn't exist naturally, then yes, you'll want to control the environment for best development. If you don't want to do this, find another bee that is
native to your area and rear that.
You'll find a bit of information on how best to raise these on www.crownbees.com (I'm the site owner)