In theory, I like the idea of large PC races options. The thing i generally don't like is when the mechanics of a race just make it hands-down superior to all other race options for common set-ups.
4e had a great design philosophy for races. Back then, the idea was that racial powers should be generally useful for pretty much any character concept instead of being useless to some/many classes. Dwarves can heal themselves and that's as useful on a wizard as it is on a fighter. Half-orc's rage gets them bonus damage, but it also applies to wizard spells. Elven accuracy works with fireball and a ranger's arrow. This design culture was so ingrained that when they came out with a race that granted a melee power, the minotaur, there were huge threads arguing about the developers dropping the ball and how to fix it. This is a great goal, IMO.
Now, if we add a large race, the OA issue seems balanced by the fact that you'll receive more OAs without the ability to make more yourself. I'm playing my second rune knight ATM, and the first one I played was a duergar that could become huge for one combat per day. Being large/huge was useful but not overwhelming, in itself. For me though, baked in bonus damage on melee weapons on a race fits perfectly narratively but feels real bad from a mechanical perspective. If I want to build a sword-an-board paladin, do i pick a race that deals 1d8 for his whole career with a longsword or the guy that just gets 1d10 forever? Do i pick the race that just deals straight damage or the one that gets +1d6 for free without expending resources? It makes sense thematically, but it feels like it creates a "must pick" vibe from a character building perspective.
I love Iron Kingdoms and supported their new 5e kickstarter. The PDF version of all of the books has been sent to supporters and, oof, the balance issues are glaring. One of the races, in case you folks aren't familiar with the setting, is the ogrun and they're essentially half-ogres. They get the ability to wield two-handed weapons in one hand and +1 to AC. From a mechanical perspective, why would you not choose ogrun if you're going to do 2-weapon fighting or sword-and-board?