Went for the middle ground here, while I don't think a human born Alien for example should have any design changes, some slight changes may be justified such as the Drone aging to warrior, warrior to praetorian etc. Or if its an Alien that comes from non-human host, then some original designs could be made (so long as its not over the top like kenner
). Making major changes to an Alien for little to no reason is not a good idea, if its not broke don't fix it