You answered that in your question.
The basic notion described is often seen on Mars rover style suits as in this image from Wikipedia.
The suit itself is the airlock. To go EVA, you climb into the suit from the back, (sort of like an Orlan space suit right now).
The difference is that the suit itself seals to the 'airlock' but does not really require the mass/equipment of an airlock. Rather the back of the suit seals to an interface, hopefully simpler than a full airlock and allows entrance/egress to the suit and thence to the outside.
Another way of looking at is, a spacesuit needs a airtight seal that can open and close anyway. Why not use that as the outer door of the airlock.
So the real question is why not surround that in yet another structure for protection from UV/cosmic radiation/impacts? Probably you would build your suit port in a somewhat sheltered area of your structure as a first draft approach to this.
I do not think the real use cases have provided far enough to identify if these are real risks or not to a suit hanging out in space for long periods of time.