That is... Super lame. Why add an entire mana type now after 23 years of the game bring around?
Generic mana =/= colorless mana
There are six types of mana, there always have been. CWUBRG.
Let's look at Sol Ring, a card which has been around since Alpha.
The cost is ( 1 ) -- one generic mana. That means ANY mana of ANY type can pay this cost. Any one of the six types of mana - CWUBRG - can meet this requirement.
Its ability produces two colorless mana, which was represented as ( 2 ). Representing the mana as ( 2 ) was actually incorrect, which is where the confusion is coming from for most people I think. It doesn't make generic mana -- "generic mana" doesn't exist. It makes colorless mana. Which is now represented with ( ♦ ). So now, Sol Ring's ability is visually represented as "Tap: Add ( ♦ ) ( ♦ ) to your mana pool." But nothing has actually changed. It still does exactly the same thing.
This matters now because ( ♦ ) is, for the first time I can think of, being represented as a required cost. So they gave it a symbol.
Basically, it's this: If you see ( 1 ) in a cost (or any number for that matter), it's asking for any mana of any color to pay it, W, G, U, whatever. If you see ( ♦ ), it requires ( ♦ ). W, G, U will not pay that.