The download protection is an optional service from Digital River ( we don't make any money on it ), which we made available because our MSFS products don't have a free Trial with an installer always available and, by default, Downloads on Digital River expire after 30 days. The download protection will extend this period to 2 years after purchase.
However, if you think you are able to store the installer in a safe place, the Download protection is redundant, so you can just remove it from the shopping cart.
And, those that lost their installer and contacted support, are ALL being supplied with a new one so no, it's not as if you don't get the download protection, and you lose the installer, you must buy it again.