I originally wanted to keep things minimal. React is not that. :P
Adding it anyway because:
When we eventually add the ability for multiple people to connect (#8) and subsequent features that become possible from that, we'll be doing a lot more DOM manipulation. No need to reinvent the wheel, might as well use a framework.
I'm told the virtual DOM will make frontend testing easier (#9).
Also 4. As I add in other things (bootstrap, d3, whatever), they're more likely to play nicely with a major framework like react than with a lesser-known library like preact.
I originally wanted to keep things minimal. React is not that. :P
Adding it anyway because: