I don't want to take away from your point, but you touched on security - I mentioned it because it was a constant pain point for both myself and for our teams. Like operations, it's something you can be good at on a superficial level, and do OK for most things, but really getting it and being good at it takes experience and time.

I don't think it came through in my post, but having a security expert (or any specialist) in the mix can be a huge help in making the product better - I know this from personal experience - you just have to make sure they're integrated, challenged, and respected in the group.