Problem

To define and rotate custom tick labels at the same time, one can use e.g. ax.set_xticks(ticks, labels, rotation=45), and pass whatever additional Text properties one wants, e.g rotation_mode="anchor". On the other hand, if one wants to just rotate the default tick labels or apply other properties (which is likely the more common case), one has to use ax.tick_params("x", rotation=45)... and some properties are unsupported, such as rotation_mode.

Proposed solution

It would seem reasonable to allow e.g. ax.set_xticks(rotation=45, rotation_mode="anchor"), i.e. calling set_xticks without actually passing ticks and labels, and interpret that as "leave the tick locator & formatter as is, but apply the given properties".