Current state of my mind: I was half way to bed when I read this answer from Louie Mantia on the "working at Square" thread on Quora. I could simply not stop myself from writing this for the basic reason that this is important. Really important to me personally.
At Square, there's chances to influence products, though I would say that most of the work done is out of direction from others (like leadership). I became frustrated with Square when I realized that I was drawing things in an attempt to please management/leadership. I wasn't trying to fix things as I thought they should be done. Instead, I was starting to design and think in Square's mindset, not my own. And most times when I voiced my opinion, I was met with conflict. I was constantly prodded to "prove my work" by creating multiple versions of things (which I had done at Apple, but never to the extent I had to at Square).
I don't know how other people work, but while I work, I try to decide what's best and scrap other things. I don't often keep things I don't like.
And though I might have seemed stubborn, I believe that when you hire a creative person, you don't hire them just for their ability to use a certain piece of software, but also for their opinions, thoughts, and guidance.
I cannot over-emphasize the above snippet from the answer. Especially the one about "…as I thought they should be done…". Most people do not realise this, almost believe the contrary. But design is as much an art as it is a science. Every product has a soul and that comes from the vision and perspective of people behind it. No matter how hard you try it always creeps in. Trying to avoid it leads into a product that just sucks at everything or is simply "average". This is why design is opinionated. This is why design and thus products that carry them should evoke emotions, good or bad. You cannot build something that everyone likes. Period.
This is why opinions matter in design, this is why designers are so damn opinionated about things. Because you cannot design by a set of rules to maximize a number. Yes that is one goal but behind all of this is the guiding philosophy, the opinion, the way one sees things. Some of the best work in the world comes from people who are highly opinionated. And for someone who has opinions, to be always told what needs to be done is almost suffocating.
The other part about what you do post hiring a creative person is important too, I think. Hire someone smart and let them do the way they do things. This is why you hired them in the first place.
I feel it almost shouts for another post where I go deeper into the why of last statement. Mostly has to do with local maxima of design (every perceived absolute maxima becomes annoyingly boring after a while), novelty and emotions in the dimension of time.
 People like to read between the lines and make assumptions. This has NOTHING to do with my current work but something I have seen too many times that it has become a pet peeve.