They're also not suitable for small-scale energy production. You have to put in more energy (to accelerate the ions towards the center) than you can get out (as heat).
Distributed grids with lots of generation points have their advantages but are really hard to manage. Somehow I doubt this is going to go to the point of having a small fusion reactor in every building, so we have to have some kind of grid. Large-scale generation is something we could plug into the grid we already have, which is a distinct infrastructural advantage - if it turns up before we have solar panels on every roof, anyway.
That's true, but I don't think there's a need to be plugged in the grid to enjoy energy generation. There are already a ton of things embarking their own energy generators (every single vehicle to start with) which aren't plugged in any grid. Batteries are also ubiquitous.
So there is definitely a need for small scale to very small scale energy generators, and dismissing a technology because it's unsuitable for large-scale generation doesn't seem wise to me.