Given that wasn't it's role in 4E (unless you would also describe 2E that way), it's hard to see how it can have "moved away from it". You really seem a bit sneering here.
I suppose that came across badly. I was making an Order of the Stick reference--though now I think about it, it's in one of the prequel books rather than the main strip. Belkar says something derogatory about Roy being a meat shield, Roy responds by touting his Master of Battle Administration from Fighter College, and Belkar asks him what courses he took, whereupon Roy is forced to admit to having taken "Standing In Front of Other People 101."
Certainly there was more to 4E Defender-ing than just literally standing in front of other people. But that doesn't change the fact that 4E fighters were explicitly described as Defenders! Their job was to lock down the monsters and keep them from engaging the other PCs. Like any 4E character, they could dish out a fair bit of damage, but it wasn't their specialty. If you wanted to lay down a lot of hurt fast, you were better off as a ranger or a rogue.
The 5E fighter has unarguably shifted hard in the offensive direction. As you yourself just observed, their options to protect other PCs are much reduced from 4E. On the other hand, they now deal damage faster than anyone else, except in the case of a wizard fighting a mob. It's a tradeoff.
Er, not really. In 4E the big deal for Fighters is controlling enemy movement, not imposing a penalty on attacks (which 5E has a moderately decent provision for via a Feat). The point was that the Fighter could go lockdown dangerous enemies and keep them from going where they wanted to - severely punishing them if they ignored him. This happened via a combination of Combat Challenge (immediate action) and OA benefits. He didn't have to hang out with whoever he was protecting. Indeed, if you were there, you'd generally already failed.
Well, now you're asking not just to have 5E fighters retain the ability to protect people, but to do it the same way it was done in 4E.
I mean, if you want fighters to be able to go out, engage a bunch of foes, and hinder their movement, that's simple enough. Give the fighter a sweep attack targeting all adjacent enemies. The attack deals minimal damage but knocks enemies prone. Does it work the same way as the 4E fighter? Certainly not. But does it accomplish the stated goal? Absolutely.
Even if you want the 4E fighter ported straight into 5E with all abilities intact, there's no reason why we need a whole separate action type just to support one class. Instead, the 4E fighter can bring her own little bubble of 4E rules and apply them to herself, thusly:
Combat Superiority: You don't expend your reaction to make an opportunity attack in response to an enemy's movement. If the attack hits, the enemy loses all remaining movement for this turn.
In some ways I think it works better in 5E than in 4E. In 4E, Combat Superiority (and opportunity attacks in general) let you jump into the
middle of an opponent's move action and do stuff while the move action sat there half-finished, which always struck me as a clunky system. Maybe it's the SQL developer in me, but it rubs me the wrong way to have actions be non-atomic.
In 5E, the fact that movement is not a discrete action simplifies matters. Each square of movement is its own thing, and no issues are raised by jumping in to act between one square and the next.
