How did they party manage level 4 without deaths thus far out of curiosity?
I’m very mixed about rerolling characters without there deaths, or revamping skills/feats for that matter. I however do make small exception I had a player come in with a character into an already running campaign (Cleric Hospitaler) and after a couple of sessions we discovered that a couple feats were causing problems namely vow of peace and nonviolence. These made actually killing enemies very problematic. I let the player replace the feat tree mostly because it affected the rest of the party.
Personally I like a party made up of highly specialized versions of characters. Cleric (Healer), Dwarf Barbarian (Tank), Sun Elf Evoker /w Spellcasting Prodigy (Crazy Damage), Ninja (OK Skill monkey /w damage abilities in a pinch). I love specialized characters...