Thing about multiple protagonists is that you gotta know how to write and interweave their respective storylines properly, with GTAV R* mentioned Michael was the first protag they thought up, and it shows. Every single beat that moves the plot forward is Mike-related, from destroying Madrazo's house, the heists, the cover up with Dave, the truth about Brad... You could demote Trevor into a secondary character or non playable antagonist and the game would play off pretty much the same
Hell you could remove Franklin entirely and nothing much would change