I think most (if not all)the Marvel movies since Endgame were good (the exception was Love & Thunder, mainly due to the directors foibles) i do think Marvel TV series are a lot more hit-and-miss
i could see it as weighing balance between complications. a low cost complication only occasionally gets highlighted. a high cost complication gets highlighted more often.
speed 12 may not be appropriate for all concepts. Some may choose to enhance powers so they can attack multiple targets, or can attack a single target multiple times. also make defenses more capable of defending against attackers with high speed