You are forgetting about security. One of these things and some explosives could do a lot of damage. Think dirty bombs. Each and every one will need 24x7 security for the duration of it's life. They simply can't be left unattended. Not impossible to do but it adds a lot of cost One of these things falling into the hands of extremists would be very bad.

The sensible way to deploy these would be in groups close to existing infrastructure in places that can be easily secured. For example de-commissioned coal plants or nuclear plants. Security also raises the cost of operation of course. Just because it is small physically does not mean the risk is smaller. So, same level of security as with a big nuclear plant. Same level of cost. But less energy. Co-locating allows you to reduce that cost.

Electricity is pretty easy to transport over 50-100 miles. One big plant servicing a whole metro is as efficient as smaller reactors distributed around. It's only when you have to transport electricity over 300+ miles where more exotic things like HVDC lines become necessary.