I'm afraid that some parts of your post are not clear to me. However if you had formatted it as internal storage no other device would be able to read it at all (other than via the phone, i.e. connect the phone to the computer via USB and view files that way). So I'm pretty sure you didn't do that. For the same reason I don't think it's encrypted, because again if you had done that the computer wouldn't have been able to read it (formatting as internal both formats as ext4 and encrypts the card, but you can also encrypt without formatting as internal, so I'm treating these as separate things even though the practical effects are the same: in neither case would your PC have been able to read it).
microSD cards are finnicky little things, and you sometimes do have problems where a card works fine in the device that formatted it but not properly in another. I suspect it's something along those lines you are dealing with here rather than any feature of the phone. It might also be an indication of a poor quality card, but frankly I've had cards from top brands (such as Samsung) fail after a short period so I'm not so sure that's a useful distinction. I would never have huge faith in any microSD card, to be honest.
I would forget your points (D) and (E): if you had encrypted it this would not have violated any laws, and if you had formatted it as internal you could always format it as portable again, so neither applies.
(I might add that replacing smartphones every 1-3 years, as many people do, is a far greater ecological offence than having to replace a microSD card on a similar timescale would be. Our disposable consumer society, based on the "externalisation" of costs (i.e. dumping the costs of your activities on someone else, including the environment) has a lot to answer for, but even if your theory about the microSD card were true, which it isn't, you would be focussing on the mote and missing a lot of planks).
