It's the only thing I don't like about Fazers and similar. You can't get your weight over the front for fast cornering, to get the front wheel properly "planted". Well, a focced arm means I can't use those sorts of bars anyway, but when I get a hustle on, it's the one thing that annoys me about an upright riding position.
The clip-on style goes back a long way Noggy. On the original 50s cafe racers it was the way to go. In the 70s and early 80s, folk used to fit Ace bars, clip-ons, and Jota bars were popular for their adjustability (from the Laverda Jota).
The manufacturers built little other than sports bikes after the first GSXRs hit the streets - they were designed using things learned from race bikes, and thank God that period is over; there was just race replica after race replica all through the 90s
Don't get me wrong, these were the flagship models where technology was developed, but at least nowadays we have some variety.
Beaten to it by Mr. limax, so there's a bit more detail for you.