@erich van loon That's because you had the already existing assumption that Mole Rats would look like they did in later games. Really if you look at it from the angle of Fallout Mole Rats being the original, it seems weird that Bethesda turned them from bear-rat creatures to literal Mole Rats.
Really most of Beth's creature designs are just pre-existing creatures scaled up (possibly with severe mange). The mirelurk seems to be the only exception tbh...