In the wider context of ereaders in general (because I am a Kindler
):
I wouldn't object to waterproofing/dustproofing in my next ereader, but I certainly wouldn't pay more for it.
I am far to busy in the bath actually
bathing, and on the beach I would have many things to do that do not involve reading. Might be helpful in case of freak downpours attacking my Kindle...
This seems to me to be very much an edge case need, and a solution looking for a problem.