I'm doubting the practicality. As aart mentioned, it'll need predator proofing. I would find it hard to see what I' grabbing for. Plus, it would make it hard to see if there's a broken egg in there or something to clean out. And, you'll need access for cleaning the box anyway.
I agree with Krugerrand, I'd like to be able to see the entire nest, as well as easily clean it out. With that particular model you would have to go inside the coop to clean out the nest.
FWIW The various comments above relate to the particular product that you have referenced NOT to the concept of exterior access to eggs.
Many folks have exterior access to their nest boxes. Some use it to avoid having to get in/out of the coop, others simply find it convenient.
Often the box itself is external and frees up coop floor space; access is from the top or the front using a hinged "door" (careful design needed to avoid leaks!).
I have seen one example where the nest boxes were inside and accessed by a "door" that was mounted flush to exterior wall.
I can relate to your desire to keep things simple but considering that the design has to be weather and predator proof as well as rugged enough to withstand daily use that may be difficult to achieve.