None so far.
When one axis of a 2-dimensional plot if overridden via xlim or ylim,
automatic scaling of the remaining axis should be based on the data that falls
within the specified limits of the first axis.
When axis limits for a 2-D plot are specified for one axis only (via xlim or
ylim), matplotlib currently does not currently rescale the other axis. The
result is that the displayed curves or symbols may be compressed into a tiny
portion of the available area, so that the final plot conveys much less
information than it would with appropriate axis scaling.
The proposed change of behavior would make matplotlib choose the scale for the remaining axis using only the data that falls within the limits for the axis where limits were specified.
I don’t know enough about the internals of matplotlib to be able to suggest an implementation.
From the standpoint of software interfaces, there would be no break in backward compatibility. Some outputs would be different, but if the user truly desires the previous behavior, he/she can achieve this by overriding the axis scaling for both axes.
The only alternative that I can see is to maintain the status quo.