As of 2.0.2 and master:

In [1]: t = np.array([(1, 2), (4, 5)], [("ABCD", float), ("EFGH", float)])
In [2]: plt.scatter("ABCD", "EFGH", data=t) # works
In [3]: plt.plot("ABCD", "EFGH", data=t) # fails with

ValueError: Unrecognized character E in format string

Passing a dict instead works -- there is no ambiguity as to whether "EFGH" should be interpreted as a color spec or a data key.

Other functions (e.g. plt.scatter) have no problem accepting structured arrays as the data= kwarg.