Excerpts from Mark Wiebe's message of Sat Feb 04 18:24:58 -0500 2012:
The names issue is a bit trickier. There has been some back and forth in some tickets, and I recall some discussion on the mailing list, but that may be long ago and without clear resolution. That this should be changed is however very clear to me, because NumPy is violating a definition in the Python documentation of what rules hashable objects should obey. The trouble is that there isn't a convenience API written yet to replace the usage of that mutability. Perhaps the thing to do is comment out the deprecation warning in the source code, and reintroduce it in 1.8 along with a replacement API appropriate for immutable dtypes?
I think we need *some* way to rename fields without making a copy of the data. I often must read from standardized file formats where I can only change the names after the fact. If we deprecate this I would have to make a copy of the data in memory to alter names, which would be prohibitive for large arrays that use >= half the memory.