I never left my CPL when taking out my DSLR. It is one of the filter which effect cannot be recreated in post (i.e. Photoshop).
It reduces reflection from objects, resulting in much better saturation and tone compared to not using the filter; a must have for landscape photography.
However, (a big however) CPL need to be constantly adjusted (called the 'angle') to get the best saturation by turning the front rim of the filter. This is a problem with drones as once airborne you have no way to adjust it.
That said, I have one in my Phantom arsenal. It could be very useful, but very challenging to get the best out.
For your need, I would suggest plain simple ND8 (for video) and ND16. A ND32 would be a good addition for beach spot; you might want 4 sec exposure in daylight to get that cotton lilke small waves.