Isn't the physical key a whole computing device with high grade storage ? I can't imagine those using cheap consumer grade off the shelf storage parts.
Enough that it's an issue when you want to store them in a highly secure way ?
I doubt that the yubico limited the number of useable keys and space available per protocol by sheer spite or trying to upsell larger "pro" versions that they never made. Using more space for encryption and other mechanism is probably a part of this, then it depends on how they allocate space (segmenting by category of data would totally be plausible for instance)
