Something like Microsoft Word would be less opinionated, it tries to be a lot of things and is only good in very few of them.
A good screwdriver is opinionated, a weird multitool that is bad at most things while also being clunky is not. A swiss pocket knife is opinionated again. Punk music is opinionated, so is jazz or drum and bass. A certain type of pop music that tries to please everybody is not. And that punk band doesn't automatically get unopinionated, because they add a little dub flavour into their music as long as they still know what they want and why.
In my eyes being opinionated is a good starting point, you then just have to decide whether the thing you decided for is the right opinion for what you are willing to achieve.
Merely importing the opinions of someone else isn't wrong, it's a phase all children (and, by extension, all learners) go through. As the person develops, they develop their own opinions, backed by experience, which either validate or disprove the opinions of their teachers; in either case, the learner has become mature in their craft, and is ready to impose their opinions on their tools, as opposed to the other way around.
But the idea of the software being opinionated—and pushing those opinions on the user—sometimes leads developers to ruthlessly strip out any affordances for using it in a way the developer did not intend or anticipate. Developers should be careful to retain at least some degree of humility and not forget that they cannot possibly foresee every practical or interesting use for a product. When you're being "opinionated", you're not just shutting out the users and use cases you're consciously forgoing, you're also shutting out some that are in your blind spots.