Innovation is hard - really good ideas are hard to come by.
Good ideas are not scarce - far from it, we can generate ideas easily. How many times have you heard about someone coming up with a great new product, only to hear people say "we thought about that 2 years ago!"? Anybody can generate ideas. Chosing the ideas to implement and aligning on the choices is the difficult part. In other words, the difficulty lies more in the culture of the organization - its management processes and mindset - than its ability to produce good ideas. Ideas without a structure and set of practices to implement them, are useless. Worse, they give the impression something will happen, and it won't.  Without a discipline of implementation people will not offer up their ideas. Why would they when nothing happens? So it is not that good ideas are hard to come by that explains the shortage of good ideas in most organizations - it is a culture of neglect of ideas that's the culprit. 

Innovation is easy - all we have to do is get a few ideas together.
If the culture does not nurture and sustain innovation, you wont see much of it. A culture of innovation is sustained by the nature of the thought processes, shared practices, discplines and behaviors.

We need to have inspiration. 
You need to generate ideas, not wait to be inspired. You may never feel "inspired", but you can generate ideas all the time.

Only "creatives" are good at innovation.
That perspective is more widespread than most people recognize and it kills any incentive on the part of most people to innovate.

Follow the process and you'll have innovation.
The process is necessary but insufficient.  To be successfully used, the process needs to be imbedded in a culture of innovation.  Without this culture in place, the organization will keep reverting to the usual framework of having to have the pathways before selecting an outcome - in other words, feasibility before desirability - which does not produce innovation.  For innovation to really happen, there must be a readiness in the organization, made up of a commitment to innovation and a culture that enables innovation.

We need to be cautious - we can't afford to make mistakes.
A low tolerance for risk will kill innovation.  Little tolerance for experimenting will kill innovation. Low tolerance for failing, especially when combined with a high personal cost, will kill innovation.