I am inclined to agree with Douglas, above, In that the corks present a snag hazard. However, I have read several posts where people have spent a lot of time and effort trying to thread the cable through a rope core. The rope can also present as a problem in that it can harbour micro-organisms which can subsequently be contaminating other sites.
I don’t see an easy cover-it-all solution at the moment, but noted that Andrew Thaler designed a 3d printable option on “thingiverse” giving removable floats. This enables moving them in case of different water density, ie. fresh or salt water - neutral density, positive flotation, or removal altogether to allow as a “drop line”.
I appreciate that these floats still present as a snag hazard and would invite anyone to come up with a better streamlined design with say a “break away” option, remembering that as a floating tether attached to say 25m of neutral buoyancy tether, there should be less chance of being in proximity of a snag.
In any case, good tether management topside and the pilot being aware of the lay of the tether is essential to good ROV work whatever you use.