Well there are actually two sides to Drain holes ( he he)
They will fill the basket from the bottom and float line if wading deep.
Without them the basket could fill from a wave and not drain.
My vote- holes since I don't wade that deep with it.

I found over all it was helpful keeping floating line untangled (with floating crud) and ready to shoot in a cast.
I also found it was helpful keeping line from tangling and catching on rocks on a jetty.
When it was in the way (when walking) I just swung it around to the back.

Overall I would rather have it and not use it at times than not have it and need it.