In fairness to the Turks, they have a very proud secular tradition. The ban was on the wearing of religious clothing in state areas, in this case universities. The fear there is the easing of these rules are the start of a slippery slope. No-one is stopped wearing the scarves outside of state institutions, so it seems up to now they had what we in the west have been looking for - one rule for all.
You mention "Rowan Williams may be odd as he likes to dress up in strange clothes, but isn't he harmless? ". My understanding is, if he were Turkish, he wouldn't have been allowed wear his robes in state areas either.
This rule has now changed, but judging by the tens of thousands of protestors on the Turkish streets I wouldn't be surprised to see that overturned.
See here:
http://news.bbc.co.uk/1/hi/world/europe/722431 4.stm