Two things to add:

1) Agreed. Writing the code is the easy part. Determining and defining what to build? That's the magic.

2) In the wrong hands, making things too easy can be detrimental. First, there's add too much, simply because you can. For instance, WordPress n00bs are notorious for adding too many plugins. Why? Because they can.

The second reason is, changing too soon without enough data, without enough user input. Yes, iteration is helpdul. But if it's borderline pivoting then that's likely to end badly. Again, in the wrong hands.