I think Lawbreakers does stand out, and I don't think the characters killed the game either. You don't need to sell a MP game on the characters you play as. Some of them have pretty cool designs, they just lack personality, but that's okay. Games like Call of Duty and Battlefield, Battlefield don't sell their MP on the personality of their characters. It's okay to make a game without anime weirdos running around. Hell, Rainbow Six Siege doesn't have especially interesting characters, but it's become one of the most popular MP titles.
I really think people need to get past that, as a reason for this games poor popularity. I think the biggest reasons were just the lack of awareness. No one that I spoke to about this game has even been aware it existed, the launch window, those that I did spoke to said they liked it, but they weren't interested because they're getting Destiny 2 soon, and the accessibility of the gameplay and how it was marketed.
Instead of showing people how to play, and suggesting that they could do all this stuff, Boss Key deliberately chose to release trailers that emphasized the skill based movement systems, and how there was a significant skill requirement just to play the game. One of the trailers proudly brands the #SkilledAF hastag. Making things worse, the game doesn't have a tutorial, or any explanation of how to play.
When I was playing on PS4, I had fair number of friends jump into the party and express the sentiment 'I played this earlier but didn't know what I was doing, just getting killed'
Things like the lack of killcams don't help with that understandability either. It's a fast paced multiplayer environment, killcams, at least in unranked games could have gone a tremendous way in helping players learn how to play.