I think it's great we can now see how our design will look on various mobile devices. And it's cool that we can make adjustments so that our design will fit on all devices.
The thing is, why can't this just happen automatically? There are other tools (I know because I've used them) that will make any block of text adapt to the device it's on where everything just fits. Isn't that the point of "responsive"? I hope to see this implemented here soon.