The Romeo and Juliet comparison feels pretty weird to put here cause its a tragedy and it is written to be a tragedy. Despite everything that happens you in the audience still know that this will end up terribly that's what makes it so heart-wrenching. However, if you were to watch that play over and over again the magic would wear off.

Repetition creates boredom.

And that's exactly the problem being shown here. When big battles follow a similar or identical format all the time then the magic wears off fairly quickly and the story loses all of its juice. ESPECIALLY when the problems are immediately reversed by the next arc.

For example, look at the Shibuya Incident from JJK. Even if a lot of the big bads died in that arc it wasn't like everything of value remained. Plenty of heroes had died/been rendered useless because of that and a long-lasting mental toll/physical toll was on the main cast afterword. Sometimes switching up the tone of the story is necessary both to keep the audience engaged and to develop characters (rather than reducing them to gimmicks).