We really can't change it, because it would break too many projects that depend on it now.
Also, this used to not be supported, and other users told us they missed it and wished objects would flip or mirror when they go in to negative width or height! So I guess it's a matter of taste or dependent on what you're trying to achieve. Still, changing things causes big compatibility problems and I don't see why we should go through that if it already does the job.