After extensive practice and using my diaphragm I've found my full voice tone being pretty bassy. (Even when singing high, the tone is still pretty bassy.)
So, is this kind of a voice used in rock/metal?
First, let's make a distinction: When you say "bassy", are you talking about the tone of your voice, or the pitch range of your voice?
Your pitch range, or voice type (bass, baritone, tenor) is not something you can change, but you can learn to expand your range. If by "bassy" you mean the tone you produce rather than the pitch range, then voice lessons with a good teacher can help you produce a different kind of tone by altering the placement of your voice. This is something that's hard to explain in writing, but a good teacher can demonstrate it for you. It would also be helpful for you to get a few lessons from a voice teacher for general, basic singing technique (not specifically for metal or hard rock) to learn what your natural range is and how to best make use of it.
If you think you want to use your own voice to express what you want to express in hard rock or metal, then go for it. There are no rules. There are bands who have a bass singer.
One hard rock singer with a deep bass voice who had quite a bit of success was Andrew Eldritch (whose real name is Taylor) of the band Sisters of Mercy. James Hetfield of Metallica is a baritone. Tom Englund of the Swedish metal band Evergrey is a bass with a powerful voice.
There are also singers in metal and hard rock who have a natural bass vocal range, but who choose to sing in falsetto. Two examples that come to mind are Brian Johnson of AC/DC and Billy Corbin of Smashing Pumpkins. Deeper-voiced baritones who use falsetto some of the time include Joe Elliott of Def Leppard and David Lee Roth of Van Halen.
Where it's used is irrelevant. No genre demands a particular type of voice, a particular sound, etc. Well, opera demands some special usage of some muscles, but other than that you find all sorts of characters dipping into all kinds of genres.
That being said, it is true that a lot of rock artists have higher tenor voices, but that doesn't mean bassier voices aren't used. Of course they're present in both rock and metal, and you shouldn't feel that your tone of voice is a problem.
I'll be honest. For glam rock, power metal, and quite a few others, tenors and high baritones rule. Certain types of music prefer baritones because the baritone range tends to be the most singable by the majority of the population.
However, if you are an actual bass, you can probably take a few tenor songs down an octave, and it can sound quite awesome. Also, there's bands out there that are fronted by a bass, and those basses have a dark, powerful voice