This structure would be terrible for conducting an ICO, the team can't properly manage their finances and are so liable to what ICO investors think and do. Many of the best projects have had times where most investors would take back their funds if they could, now they've gone on to be tremendous successes.
I don't think it will be terrible for ICOs. In opposite! It will bring more investors into the project, more will invest and the money will be more they are investing because they can feel safe about this ICO being no fraud because it's possible to get the investment back.
Of course, there can always be some investors sending back money after the ICO for various reasons, but the additional funds from being received due to being transparent will be much more compared to funds returned after ICO.