[thxbb12]

Having a low enough ISO setting to use fast glass in bright light is less of a problem, as it can be easily worked around using a ND filter.

 

I find the use of ND filters a real pain in the butt!

Between having to screw a filter every single time I need to use f/1.4 or f/1.8 and being able to dial ISO 80 at the touch of a button, there is simply a world of a difference in terms of convenience.

Plus, you need different filter sizes.  If the lighting changes, the filter may force you to bump the ISO which is not desirable or unscrew the filter....  It's just super annoying, plain and simple.

This is especially true when it could easily be otherwise if Oly or Panasonic had followed a route similar to what Pentax did with the K5.