you're probably right. We couldn't allow players to destroy the tiles as the "grid" is formed wherever you place the first tile, it doesn't use any built in systems. So if you were to break a tile between two "islands" it may break more gameplay. However, there are ways around this like ghost tiles.
It's a good idea though, especially destroying for a price. (A high price ;) ) we just didn't have time to explore our options :)