I'm not sure if you picked the most minor nitpicks on purpose but none of those are really why I'd say it's a bad movie. In my opinion it's because the execution is just poor overall. If you watch the newer suicide squad it does pretty much all the same things as the first one but better.

They're there to fix a problem caused by the government that sent them. Harley deals with attraction to a toxic and evil man. Some have super powers and some don't.

The difference is the characters are interesting, likeable, funny, and you get to learn about their back stories and see some character development for all of them. Everything in the original just comes across as forced and only a few of the characters get any real focus.

I sum it up as the difference between killer croc and king shark. Killer croc just looks bad and is basically a 1 dimensional black stereotype that's just there and maybe does something twice the whole movie. King shark is a dumb lovable monster that bonds with the team and actually has a presence beyond monster guy go do the thing we brought you for. They're both supposed to be major parts of the team as the heavy hitters but you could take killer croc out of the first one and the movie would be unaffected.