I think because the Toa are seen as powerful heroes, and were in the main characters in bionicle, so naturally people would want to be some one like the main characters.
I don’t know what this should be under to be honest.
And I would say most people portray themselves as Toa because the Toa were the original heroes of the story, the most powerful ones and the most iconic imagery in Bionicle as a whole.
I’m a hero too, that’s probably because it’s cool, but I’m not a toa, considering the rules of my universe aren’t the same, so I’m what I call an “elemental master” but yeah, one of the most over powered.
So my theorie is that everyone want to be better than in is real life, they want to be as their dream, live incredibles adventures, leave their boring lifes ! And here’s a fact : the only goal of the lego themes is to makes us dream, even after the death of the G1 and 2, we’re still dreaming and that’s a thing we shouldn’t lose, dream, is the only way to escape our world. The imagination is one of the best thing in that world, so keep dreaming guys.
@Chronicler has a toa character but with our matoran Fa I believe is his main because he is the chronicler in our story of Karhi Nui. I of course am generic with a toa but have an alternate universe which is not a toa.
I have five “Self-Mocs”, each embodying a different facet of my personality. There is the obvious Steampunk Tahu, who I’d say I didn’t choose to be a Toa, he just already happened to be. I also have Toa Gavan, who embodies the good, brave, and courageous aspects I gave him, although I identify more with the Matoran version of him, which is the most canonical, as he is meeker and not as courageous. Then there is Toa Vani, the Toa who would like nothing more than to be a Matoran again. She fits the more compassionate, calm, and thoughtful side. Then there is Toa Navag, although Toa is a stretch, as he was corrupted by shadow, and is fascinated with trying to emulate the Makuta. He fits the darkness and hate, although exaggerated. So, I wouldn’t say I have a “Self-Moc” as much as I have a band of characters I can relate too.
My self-MOC used to be a Toa, but frankly I think it’s a bit cliche at this point. The Bionicle community has probably, at the very least, built double the amount of Toa that existed in actual canon.
As to why that is, I would say it’s probably because the Toa are the heroes, and they’re the ones with the super cool powers. Very rarely do you get a person who wants to make their character the powerless villager, or a hero past his prime. Everyone wants those awesome Toa powers.
It’s not wrong to build a Toa, but personally I’ve grown away from making them as a whole. It’s hard to build interesting characters when most Toa usually fit a pretty standard mold and only have certain sets of powers. I find it much more creatively liberating to build a character without the concerns of canonical accuracy or labeling. You could make the argument that you shouldn’t let canon dictate your builds, but I would argue that if you’re going to do that, you might as well just go completely original. Now I could just build a character who happens to have elemental powers, but I can put that character in whatever Bionicle-esque world I want.
I think that a big reason is also that a toa is an easy template to start from for both design and story. Say you’re new to the mocing hobby in your early teens and you’ve mostly had experience building sets. You want to make a character to represent yourself, but the creatures and whatnot don’t feel right and you don’t have many ideas. Fear not, for you have the Inika build and a ton of lore to fill with original content. Just slap some new color scheme and you have your first original character in some unexplored location on Mata Nui.
Bionicle’s lore was accessible enough to partake in it.
In my case, my selfmoc started as a dragon as I wanted something more unique.
Around that time on mocpages it was pretty popular to make MOVs of others’ selfmocs, so I tried to cash in on that and made new toa version that would be easier to reference from.
Obviously that failed, and the build was a bit fragile, so I went halfway backwards and built a simple yet sturdy lizardman. I started to write a story, so this version stuck longer, and I upgraded it over time.
Eventually I stopped the story and started another one. This prompted a new form for my selfmoc. Still reptilian, just promoted to dragonman. This is the version that has continued until today.