Human versatility in D&D 5E (which is what the game is based on) includes a free feat. This is not a suggestion to change the rules. It is a suggestion to follow the established rules of the game.
As it is, there is really no reason to create a human player. Every other option when selecting race is superior. Restoring the nature of the human versatility to also include a bonus feat would add flexibility in character creation and allow for human characters to be closer to on par with the other racial options.
How are dwarves superior to humans? There is no reason to play as a dwarf other than for aesthetic reasons. Reduced base movement speed for some proficiencies that you would get anyway if you choose to play a class that rely on armour and melee.
For humans they replaced the extra feat according to the core rules with something that indeed is a lot worse, but the mountain dwarf is supposed to get an extra ability score point and they simply removed that without giving them anything else in return. They were simply nerfed because...elves weren't already popular enough I guess?
