The Fighter / Bruiser Conundrum, aka "Nerf Irelia"
Several times now I've seen some Rioters (and Morello specifically) mention that they want to rework the entire Fighter class. They've referred to Fighters as a "ball of stats" and that they want to move away from this and towards each champion having their own niche.
So let's see what we have to work with. The following 34 champions consider Fighter their primary trait according to the LoL Wiki (with 23 additional champions flagged as fighters for their secondary trait).

(Of these champions, Yasuo, Aatrox, and Vi are the most recently released.) So what kind of patterns do we have here? Which of these champions already have a good niche? More importantly, what does a Fighter actually do? What is their role on a team?
We are offered this description: "Fighters are champions that blend the attributes of a damager and tank, combining moderate to heavy survivability with a portion of the damage of an assassin or marksman (essentially half tank, half DPS). They lack the front-loaded, destructive damage of their pure DPS counterparts, but usually have abilities which increase their damage output or abilities with high damage bases, making them deadlier in the early game. Fighters can build to be extremely survivable, but the key distinction between tanky fighters and true tanks is that tanks are designed to draw damage and disrupt enemies, while fighters deal damage. In a team fight, fighter champions can surrogate the role of a tank or assassin, and many have powerful fight-initiation abilities. With their special blend of defense, damage, and mobility, fighters can pierce through enemy lines to reach and destroy squishier targets while withstanding moderate damage."
This seems to suggest that Fighters are a flexible role and can build either durability or damage based on what the team requires, which only partially matches my own observations. Generally a given champion will favor one or the other, which is interesting because I recall seeing a red post that divided fighters between those who wanted to dive the enemy back line and those who fought on the front line, and I think there are some parallels there.
That said, I think this is a large part of the problem. Fighters are so vague of a category that individual fighters are defined by how they resemble a different category (read: tank, assassin, 'marksman', etc.).