Plimsoles worn all the time can make the feet hot, sweaty and really moist, making the skin prone to bacterial and fungal infections.
Ordinary shoes really do support the feet considerably better than plimsoles, which are so lightweight and flimsy they can damage the growing foot. So check those gym shoes often, at least every few months and look after those tiny feet. Keep your eyes on the lookout for mossy foot, cankers and egg-burn.