I’ve been thinking about it and I want to share.
In short – earth ponies are useless as a race.
Now, let me explain, why.
Why are unicorn special? Because they have magic.
First – telekinesis. It’s a great power, actually. Take biotics from Mass Effect, who are capable of warping atomic bond, create singularities, fly, lift heavy objects making fly others and many uses. Remember also Ermac from Mortal Kombat. Thanks to his telekinesis, he’s one of the most fearsome opponents, and he can just tear apart a man without much efforts.
Second - magic. Nuff said. Reality warping in it’s finest. Maybe not like Discord does it, but to similiar level.
Pegasi can fly and control the weather.
Unicorn have the school of gifted unicorns, where nopony else can study.
Pegasi have Wonderbolts where nopony else can serve.
What earth ponies have where no other pony can serve? Nothing.
Now, what are they capable at? Pulling carriage? Please, anypony can do that. Sweetie Belle was able to pull a carriage, full of luggage and other stuff without much strain.
Garden? Anyone can do garden. I know many people who grow vegetables and flowers. Unicorns can do it even better than earth ponies, because they have magic.
Strenght? No way. Rainbow Dash was able to beat Applejack in hoof wrestling. Also, a single Unicorn can easily overpower any number of earth ponies with telekinesis.
So, this is my opinion. If any of you have something to add, go ahead.