Unless your Ohms are low enough that you are running into current limit or high enough that you are running into voltage limit, it actually is likely pushing 200W:
The screen values are averages of every 250 milliseconds (four times per second -- in the beta custom fields showed real-time but it was changed because numbers changing hundreds of times per second are really hard to read), so (for example) if it only takes 50 milliseconds at 200W to get to temperature and then you're at 20W for the other 200 milliseconds, that interval is going to show (50/250)*200+(200/250)*20=40+16=56W -- the average power over the interval.
It does take a tiny bit of time to ramp up to 200W, but most likely what you are seeing is due to time averaging of the displayed value. 200W is a lot and often isn't needed very long. A thinner wire will take less time to heat, that's all, in this case less than one screen update interval. The control system is rather fast.