I do not see any negative points in freezing level, you gain advanced refines faster, you will have less difficulty in SA, Team Instance, Matsuri Challenge. Players can only attack you in the convoy with 15 levels of difference, being level low you decrease the risk of being attacked. You get the Limit of Sun / Moon coins just doing TI, SA, SWB, Matsuri, DB. The only kind of experience you can get is Team Instance, all the rest does not have to be done (Kurama and Jinchurikin events).