In a perfect world yes, what you say makes sense and let's just even assume he will give a lot more effort on defense for the Cavs.
1) Will he be willing to accept a smaller role on the Cavs I.e. Stand in the corner and wait for the ball? Or is he going to be the ISO Melo and ask for the ball in the post.
2) I absolutely abhor the Olympics argument for many reasons. They play against shitty competition, small sample size, he had one good Olympic run and the rest were mediocre at best. To top it all off, that was a long time ago and he is much older/ slower now.
3) You say Melo has all these offensive skills but do you really see him scoring efficiently against the likes of Draymond, KD, Iggy, and Klay at this stage of his career? Love definitely had his struggles against GS but he was money for the most part of the playoffs. I would bet Melo would see a similar trend if he were on the Cavs.
4) Melo may not score 9 and 6 points but he will take a ton more shots to get them that 15+ (Volume shooter that is not highly efficient versus top defense). At least Love knows when he is off and will stop jacking up shots and tries to focus on other things like rebounds and defense.
Finally, Love is a better passer (not talking about stats but just the ability to make tough passes), he is obviously known for his TD passes but he is also very good at post-entry passes that lead to a ton of buckets for LeBron. His PnR game with Kyrie is also very efficient. I don't remember the last time I saw Melo run a PnR.
Honestly I could go on and on.