The difficulties with such studies is that whilst they are interesting and provide some useful pointers, they blur levels of meaningful detail which in this case relate to individual difference. It is a simple fact that people are different - they are motivated by different things and at different times. Their needs are different. Whilst 45% of respondents might have said that a good work/life balance was their main motivator, what that means will vary for all of them (and of course 55% didn't report it as their main motivator). We should also probe whether such external factors are actually motivating ones. Work in the area would suggest that they aren't. It is most likely to mean having control over working hours/location and flexibility.
In motivational science terms, the aspect of control is the most important feature. Unfortunately, the kind of approach reported seems to imply that people are a passive lump to which things can simply be done in order to achieve a different outcome. This thinking is probably at the heart of most disengagement and lack of motivation among people!
To enable people to do their best we need to engage with them (with each other!) as unique adults who have potential, and work with them to understand their drivers, values and needs. In collaboration, employer and employee may then create an optimal working arrangement.