It is important you study the white paper because you get know the details about the technology and how effective it is implemented. It is also important because, you can easily spot out the token metrics, strengths and weaknesses of an ICO if need be before making the final decision on whether you wish to invest or not.

This becomes important when you want to be a part of project for long term. Else if you are only looking to make quick money through trading, I think it is fine if you miss some whitepapers.

Cheers!!