Imo, I think it depends on what bungie is going for, if they really want you too get into the story they should go for a higher level cap it would be fun questing while learning more about the lore, but if they would rather have you doing the fun content instead of questing all the time they should have a low lvl cap, although idk how the leveling system is going to be like I wonder If you'll be able to level without questing & grinding random npc monsters, say you can level by just pvping all day in a game mode.