Nobody including Niantic would ever have dreamed that Pokemon Go would be as huge a sensation as it has been. Nobody. And they have smartly realised that this opportunity is potentially fleeting and so they need to capitalise as quick as possible i.e. grow into other regions.
To expect them to do accurate capacity planning is ridiculous. Likewise it is ridiculous to assume that they can react any quicker than they can. It's very hard to scale quickly whilst still maintaining a high level of uptime.