I disagree (per https://github.com/mapbox/tilelive-vector/pull/48#issuecomment-40439279).

I'm not proposing changing the default behavior, just introducing the flexibility to output arbitrarily sized images (independent of scale). Requesting a non-standard image size would necessarily be done through `tilelive-vector`'s API, so it would be assumed that it would be done with appropriate foreknowledge of the visual consequences.