What are the most common barriers to creativity in product design?

As a definition, Creativity is the ability to make or produce things using imagination or skill.  Skills to discover or narrate the actual pain point of the user/process and convert it into meaningful designs using imagination. 

Individual biasedness towards the user/process, lack of understanding, assuming things, and not having enough imagination bandwidth, challenging the status quo are the common barriers to creativity. 

A lack of understanding of the end user, their abilities and how the product fits into their general workflow. We sometimes constrain our ideas because we think it will be too complex for the user or will frustrate the user in some way, but a deeper understanding of the user might loosen those constraints.

In my view, one of the biggest hurdles is striking a balance between user needs and business goals.  Market needs and preferences change. What was validated a year ago might not hold true today. Periodic revalidation ensures your product remains relevant.  I think these have a very strong impact on design both directly and indirectly.