This whole debate reminds me of the joke about a mathematician, a physician and a few other scientists trying to "prove" that all odd numbers are prime numbers. Three is a prime, five is a prime, seven is a prime, and at that point, one of them stops and considers this to be enough evidence.
Yes, it's true that we haven't seen any Gorons yet that were obviously female. This leads to three possible conclusions.
1. The Gorons evolved completely independent from most of the other lifeforms on Earth (or Hyrule), there are no female Gorons, and Gorons reproduce drastically different from other Hyrulians, either through some sort of mitosis or by growing out of rocks.
2. There are female Gorons who look and sound just like male Gorons. Just like dwarves in some works of fantasy. That all Gorons who we have met in the games were identified either as father, son, or by another male denominator is purely coincidence or perhaps owed to the patriarchal society of Gorons.
3. There
are female Gorons that look different enough from males to be distinguished, we just haven't seen them yet.
Occam's razor would indicate that the third hypothesis is the likeliest scenario. Now of course, we can only know for sure if Nintendo directly adresses the situation, either in-game or in an interview. But until that happens, I just think that 1 and 2 need too many new assumptions to work.
Also notice that we have only seen one male Gerudo so far, and he's sealed away in the Twilight Realm or the Dark World for most of the time. It's not uncommon for a Hyrulian race to have a huge gender imbalance.