I'd also argue that even if all else is equal, a flashy visualization is worse than a conventional one, as you generally do not want to draw attention to the presentation if your aim is to convey information.
Fun counterpoint is that a flashier visualization may be 'better' than once optimized for accurate and efficient information conveyance IF it causes people to spend more time on the visualization. A flashy infographic conveys information less efficiently than a good chart, but if it causes people to engage with it more you may end up communicating your information to more people.
