All depends on which GoPro you are talking about? Go Pro Hero 5 and newer are water proof to 10 meters without a case, so no need for the extra weight!

I have a 7 Black and have never had any issues using it as is.

New ones including hero 7 have high pressure water resistance, so no need for housing. That said, there are many people who had fogging problems. I still use housing (hero7) since I had it already, but I wouldn't buy one if I didn't have already because they are quite expensive.
Pros:
- scratch protection, no need to wash sand and salt from gopro after session
- peace of mind in terms of waterproofness
Cons:
- bulkier and heavier
- you need to remove camera lens protection
- better microphone performance but inconsistent (water blocking) without housing

I've got a go pro 4 ,yes it needs a housing ,after that you are housing free ...i use a session ,light on the head ..why did they stop making them ,
when mine dies I will cry

windaddict said..
All depends on which GoPro you are talking about? Go Pro Hero 5 and newer are water proof to 10 meters without a case, so no need for the extra weight!

I have a 7 Black and have never had any issues using it as is.

It depends on how they rate 10 m.
A 10 m watch is only good for in rain or in the shower . If swimming with a watch the stroke force when hitting the water can be much higher . In watch terms you want 50 m or more just for swimming.
A GoPro at the tip of a mast during a high speed catapult would create way more than 10 m depth waterproofness.