I like the idea behind your approach. Elegant and simple indeed.
I agree with the above comments from @Hemlock
Here are a few additional details, don't hesitate to correct me if I'm misinterpreting or missing something.
1) The Brawler essentially has a single option at any time. If you are not already grappling, you can grapple (or grab). If you are grappling, you can restrain. The Clinch Fighting is nice little bonus ability, but it is likely to be rarely used. The other kits pretty much offer three useful effects. Of course, being able to grab an opponent is considerable. I'm only discussing player choice here, as opposed to balance.
2) I think that Brawler would benefit from some restrictions. First, having at least one hand free to attempt a grab. Or, do you see allowing the shield-bearing fighter attacking with his sword also attempt a grab? And then, can the Brawler wielding a two-handed weapon make an attack when it is already grabbing someone? I would also restrict the further attack to being made with a one-handed weapon, or unarmed strike (such as a head-butt).
3) In view of the above, I'd consider amending the Brawler to: (a) allow unarmed strikes to be made as a bonus action; OR (b) allow a grab to be made as a bonus action; (a.k.a. player choice!) AND (c) give him some additional efficiency with unarmed strikes; AND (d) restrict grabbing to being doable only if one hand is free, and then further attacks to being doable only with one-handed weapons or unarmed strikes if the warrior is already grabbing someone. So the Brawler would be good punching AND grabbing, and could use his punches or headbutts or kicks while he grabs, essentially allowing a warrior using a two-handed weapon to grab and then put that knee where it hurts before he restrains.
4) The Manoeuvering Attack appears difficult to visualize in some instances, to me. Let's say that the stealthy enemy archer behind his 20 melee allies is firing arrows at your party from 100 feet away, behind his cover. How do you manoeuver to force him to move? I would suggest limiting the manoeuvering attack to enemies that are adjacent or within very short range; and additionally allowing the power to be used on an ally instead, then automatically succeeding. Although, it is then closer to a tactical warlord's powers instead of a scout. Perhaps you could consider switching the Distracting Strike with this Manoeuvering Strike.
5) Sweeping Attack allows damage to be automatically dealt to a second opponen when you hit a first opponent. I'm unsure this is balanced. Having this power, I would most certainly use the low-AC minion next to the high AC Big Bad Evil Guy to attack with Great Weapon Master to deal a maximum of damage to the minion and then apply that damage to the BBEG. This would require the DM to use artificial strategies to avoid this kind of situation.
6) Trip Attack: Knocking a creature prone normally allows the creature to resist by a Strength OR Dexterity saving throw (creature's choice). I would also allow either.
7) Lunging Attack: does it increase your reach? Does it change the threat range for OAs?