Ok, so I just read the grappling rules, and I'm left wondering to myself, "what's the point?"
Oh it's a thing baby! See
here.
In a subtle way, it might be the most powerful build there is.
Here is the intro section (thanks to -ktkenshinx- for this):
1. Why grappling?
Ever wanted to armlock an ogre? Drag that cowardly, dual-wielding ranger over to the cliff and chuck him over? Hold down two orcs while kicking the third? Thought so.
Why grapple? Easy; Grappling is unfair. Most enemies in the game get their strengths from unrestricted movement, free reign to cast spells, ability to target certain PCs in the party, high ACs, etc. All of that is totally shut down by a good grappler. Although it looks like an innocuous condition, being "Grappled" (and/or Prone/Restrained) is a serious hindrance for most enemies. Being able to impose it on them at will, with little or no hope of them stopping it? That's how you will dominate a battlefield.
When thinking about mechanics, I like to think about their axis of interaction. How are they interacting with an opponent? Attack rolls are opposed by AC. Spells are opposed by saving throws. High damage is opposed by high HP. Looking over what monsters we do know, all of them have something in common. They are generally well prepared to fight attack rolls/spells/damage, by virtue of high AC/hig saves/high HP. Not every monster has those traits (bless your soul, little goblin), but over the course of your travels, you will often encounter monsters that directly counter these angles of interaction.
Then there's grappling. Grappling is a skill contest based on the Athletics skill. Most monsters, even with their high strength scores, have the Athletics/Acrobatics checks of a 1st level commoner. Sure, you will fight monsters that can't get grappled (Ghosts...why did it have to be ghosts...), but the vast majority of monsters will be crying uncle against a good grappler. That lets you dictate how they move, who they attack, and how they take hits, etc. That is a degree of battlefield control most classes can't boast.
Overall, here are the pros and cons of grappling in 5.0.
Grappling Strengths
Very hard to interact with. Most monsters are about as good at Athletics/Acrobatics as a first level character.
Negates mobility. It's amazing how many opponents rely on movement and how many can't do anything once that speed hits 0.
Makes monsters easier for your party to hit. Grapple them, knock them prone, don't let them stand up, don't let the run around. I hit. You punch.
Cripples offensive capabilities. Grappled monsters already don't get free reign to choose targets or use their weapons. Now give them disadvantage on top of that.
Combo potential; Grapple a spellcaster in a zone of Silence and no one will hear him tap. Hold two guys in place while your Wizard rains Fireball on their heads. Plant the badguy on the ground as your rogue stabs away. Jump of a cliff while holding your targets. The possibilities are endless!