Many stores have long lease agreements and have found it difficult to scale back. KK didn’t have much of a High Street presence unlike WH Smith. They have presumably been hit by people not buying reading material and stationery. It’s all on line now or at the supermarket and a High Street shop dedicated to newspapers, magazines, greeting cards, books and stationery is not needed. Hence their problems.
I don’t think shops necessarily over expanded. Just look at all the new shopping centres that were built not so long ago: shopping became a leading pastime. I think niche shops like KK, who didn’t really change their offering, are likely to struggle. I would think KL sales have just dried up.