It's great to be nice. Nice to customers, prospects, and partners. We want them to like us and we want to treat them well. It's also useless.
Nice doesn't change anything. It's hard to value. It's boring and bland.
Opinionated isn't always nice. It's challenging. It decides that something is wrong with the current system. It leads to change.
Opinionated isn't rude, but it isn't easy. You cannot get around it.
When you get busy doing what you do, be opinionated. Form an opinion. Defend that opinion. Challenge the status quo.
And while you are doing all that? Be nice about it... It won't hurt.