I was thinking about 5E's races the other day (considering joining a new 5E game in RPOL and thinking of characters I might want to play led me to this).
One thing I like about 5E is that most of the races get a choice of subrace. These are excellent ways to differentiate the various types of dwarves and elves that populate most Tolkienian fantasy worlds, and also a nice way to customize 5E to suit your world. If you don't have Dragonlance style tinker gnomes in your world, do away with that subclass, or replace it with something more fitting.
But I realized there's an obvious place where WotC's designers dropped the ball: The Half-Elf and Half-Orc.
Neither one has subclass options. Now, some might say that's because they're part of the "less common" races section. But Gnomes are too, and they get subclasses. Dragonborn, by selecting one of five types of breath weapon/energy resistance, have de facto subclasses.
Why not the Half-Elf and Half-Orc? As they stand now, the HE is fairly split in favoring elf and human traits. The HO, on the other hand, is VERY orcish.
Why not subclasses for both, one which favors the human side, and one which favors the non-human side?
If I ever get around to running a proper 5E game, I think I'll work something up for these races.
Oh, and Tieflings, too. They could easily have demonic/devilish/daemonic subclasses (or a subclass that favors their human ancestry as the HE and HO subclasses I suggest) to choose from. But I'm not a huge fan of the race, so I might just leave them as is if I don't just disallow them period.