My attitude on this is that "there should be only one obvious way to do it".  Adding this way of doing the transform means there's two ways to do `transfrom_to`, essentially, and this one is more confusing because what happens if I do ``ircs2 = coords.ICRS(fk5_2, equinox=J2002)``?  It's not immediately obvious which of the two equinoxes is the one that should be taken. But there's no ambiguity at all if you do ``fk5_2.transform_to(coords.ICRS(equinox=J2002))`` - you can just read off the intent.