Agreed, and very insightful. making tougher maps with having to restore pre-burnt tiles is actually a really good idea, too!
I added those cards for 2 reasons:
1. In case you end up with too many burnt tiles or built tiles and can't build a camp, for example. To prevent the player from getting locked.
2. Every deck of cards needs some 'lower tier' cards you can discard or care less about, imo.
Other possible use cases for them in the future are:
1. Allowing the player to expand the map, and that it could only be done with non-structure cards.
2. Allowing the player to destroy buildings with those cards, so they could build better buildings.