small local bookshops are inherently worth protecting. Why is that?
Because you need many, many competitors in a market for it to actually be a market. The amount of large corporations any market can support is limited and fairly low, general business wisdom has it that it is around 3-5 with the first 3 being profitable and two or so more being able to just barely make it.
If you want many participants in a market, most of them will be small. That is why small shops are worthy of protection.
You also want to have employment in your country be fairly even, and not have some areas with high demand and low supply and some with low demand and many unemployed, which is why local shops are worthy of protection.
Really, you just need to use your brain a little more and it's all very simple.
Perhaps the space the bookshops used up can be replaced by coffee shops
Maybe, but this is not at all about bookshops being replaced by something else, it's about small competitors being driven out by large competitors, so put the strawman away again.