That's why starting areas based on races is important.
Heck make every race has a few options to start in.
Also, make content for all kind of players. The soloers, the Duo, The Group. Indoor and Outdoor. Easy and Hard. Don't forget other dimensions of game play which everyone actually neglect. Crafting, Farming, Harvesting, Hunting, Stealing from a City, Guarding a City, Job Career in a City... Vanguard tried the diplomacy thing but let's face it, it's just a Mini Card Game. Let's expand beyond the "combat" game and you'll get a player base that have different preferences spread out all over the map.
You see a dungeon being overrun?
Easy solution, improve the other deserted dungeons of equal level/difficulty or create new equally good ones. How hard it is to create a new dungeon with all its lore and NPCs? seriously? I would do this for free for any developer if they provided manageable tools
For once consider balance as an overall world thing and not only for class-to-class power struggle.