I think that the main problem with bruisers isn't so much the bruisers fault...
Historicaly if we look back at season 2,3,4 and 5, bruisers and divers had more damage output than marksman. Since season 6 marksman have been dealing more damage than bruisers and so it makes bruisers less appealing and outshined.
If you think about it, back then if you were playing a diver you didn't even think about going into a fight often times picking up multiple kills or at least causing some serious damage to the enemy team before dying. Now when you play a bruiser you have to think about it because One you probably are going to die, and Two your only job when engaging is to kill the enemy marksman and if you fail the game is lost.
Markman are just too powerful as a class whole and it's bringing the test of the game down because of it.
I mean if you really want to boil it down look at tanks. Tanks back in the day took almost a whole team to take down and it took at least 10 seconds. Tanks now last maybe 3-4 seconds max and even less if they have a vayne. I guess the trade off is that tanks now can actually kill you bug that's not really their intended job. Damage is still simpley just too high.
We could just nerf everyone's base AD by 5 and see where that leaves us.