I know about the problem with glass domes from my own 2155 / 2185 cams. But never been a big issue here.
However. I could see a problem in dust, snow and spiders, collecting in "corners" of cameras without glass domes. And I think it might be easyer for unwanted people to manipulate with the direction view of the camera, when there is no protection dome on the camera. But thats just my thoughts......