I very much dispute the claim that devs are not allowed to think big. It’s just that they take the easy way out. After all, others are taking care of the visual design, requirements engineering, reporting, controlling and whatnot, right?

It’s fine, really. But then please don’t try to overstep the role you assumed.

In my opinion, it is critical you do both: Know the big picture, the vision, build a technological vision based on that. And then you must work on this, in bite-sized pieces. From my experience, in all but the smallest projects, not working iteratively (“experiment”, as you call it) is pretty much a guarantee to build the wrong thing from a user/customer requirement standpoint. Not having the technological vision is also guaranteed to result in a steaming pile of tech debt.

I don’t see a problem with providing reasonably accurate long-time estimates either. Build your technological vision and you’ll know. Everybody knows and will understand that substantial requirement changes or newly discovered requirements will change the timeline.