I don't think I ever really played with premade characters in anything but 2 very experimental oneshots in new systems, but I feel it's worth differentiating a tabletop system's premade characters that the company made with a premade character you made yourself a while back for a different game and just pop into a new story.
Both aren't specifically made for the current campaign / party in mind which can make things jarring. It sometimes bothers me when I see players having a very nonchalant take on party building and don't even want to know what the others have before the actual game starts.
Yes, there is no need to 'optimize' a party, but also yes, more likely than not, if 2 other people fill the exact same role you wanted to fill you will feel a lot less special and cool compared to the guy that actually does something unique.
Even more important: Would these dudes even get along/have reason to stick together? Mechanics aside, playing edgy assholes is far from uncommon, or even a bad thing in the right context, but if the rest of the party are heroic goody two shoes it gets really awkward to find excuses to keep traveling your character.
But I absolutely got on a tangent there. Personally, I always prefer making my own characters. I enjoy the mechanics part of it, finding fun synergies or gimmicks to build a person around, I love trying to intertwine backgrounds with a pal and especially to make sure my character has some kind of connection to the actual story going on. Premade characters, if taken at face value, just can't do that unless they were literally designed for specifically this adventure compared to a more generic approach.