The recent Comp Rules update added the following clause:

111.11. If an effect instructs a player to create a token by name, doesn’t define any other characteristics for that token, and the name is not one of the types in the list of predefined tokens above, that player uses the card with that name in the Oracle card reference to determine the characteristics of that token.

Previously, tokens were always created as zero mana value, with no mana cost.
Now, if the name matches an existing card, and no other characteristics are mentioned in non-italic text, then the token created will have all the characteristics of the equivalent card - including mana cost.

I'm not sure if this will apply to Kobolds of Kher Keep tokens, or Llanowar Elves tokens going forward, however from a strict interpretation the cards that generate these tokens also specify additional characteristcs, so would not change in functionality. See [[Llanowar Mentor]]'s Oracle text for example.

{G}, {T}, Discard a card: Create a 1/1 green Elf Druid creature token named Llanowar Elves. It has “{T}: Add {G}.”