My .02....
For me the outside shower is just one of the useless things they still include with the trailer that doesn't have much value to me...but is one more thing I have to maintain (winterize, check for leaks, etc.)
I put it in the same category as outside speakers. The ones they install sound like complete garbage, can be a leak point, and are no longer necessary with all the fantastic sounding, portable bluetooth speakers that are available.
But you might find either one something you can't live your RV life without.