Changes in bitcoin are possible and happen. For example, if we want to have more divisibility, we have to change the protocol.
To allow more complex transactions, the protocol is going to be changed soon.
those kind of changes don't do any harm to my money,
yours would.
and i gave you a few examples how it can hurt me.
if i'm a non-techie person and want to "hoard" my coins offline, using BitBills for example, you want me to destroy them after X years (and import the BTCs to an online wallet), just to not lose my coins.
i bought those BitBills for a reason, i paid for those coins, it's up to me what todo with them.
no protocol-changes ever should change that, or at least should be on their own fork (maybe i would use that fork too, by choice, not forced to).