The storage is the problem. How do you store them?
edit: I am thinking mainly of espresso and now that I fully read your comment, I see you acknowledge that. Espresso in a sealed bag is pretty good for months. But once you open it, the flavor changes day by day and after a week or so the special qualities are basically gone. There are various things you can try but I have yet to find a great solution to this.
This has been blind tested time after time, and at best nothing beats out a carefully opened bag that’s folded tightly. Many of the fancy containers are actually worse.
I think there are a couple of different things at play with espresso beans in regard to aging.
Flavor compounds: my understanding is that flavor compounds continue to develop post roast, with the consensus suggesting that 5–10 days post roast rest is required to develop peak flavor.
Outgassing: beans continue to outgas after roasting, and a tightly sealed bag wouldn't prevent it. However, once most CO2 has been lost, it doesn't necessarily imply that the beans are stale. Espresso techniques are designed around the back pressure from outgassing, and 'flat' grinds would pose a problem. I'm sure it can be addressed, though - by reducing flow rate, for example.
Stale: The real issue with aging is the oxidation of coffee oils, and that's where proper storage is required.
edit: I am thinking mainly of espresso and now that I fully read your comment, I see you acknowledge that. Espresso in a sealed bag is pretty good for months. But once you open it, the flavor changes day by day and after a week or so the special qualities are basically gone. There are various things you can try but I have yet to find a great solution to this.