Sounds a lot like tonics from BioShock. Plus, take into account the way that people tend to trust things that have Latin names and are endorsed by a kind and professional-looking older man in a white lab coat. I tell people about my condition IRL, people say vampire and look at me weird. I say I have porphyria, and suddenly it's all very respectable. You sell something based on the concept that it is safe, tested, and quality-approved. Considering the cyberpunk nature of Shadowrun, selling something under the false pretense that it's safe is one of the hallmarks of megacorporate tactics, as they answer to no one but their shareholders, and technology and ambition often outrun safety or morality by a longshot. IIRC, Ares has a habit of dropping their prototype weapons on the street, whether for gangs, as payment for runners, or whatever, to get free field testing from time to time. No reason to think other treatments wouldn't get the same. How many old folks on the streets with a glitched-out cybereye or arm possibly got there because that wiz piece of gear turned out to be a glitched out prototype?
As far as the corps go, I've always figured Renraku has been mostly out of the spotlight...
From a Writer's perspective) because they were the primary metaplot focus for so long. Gotta turn away and look at other things now, before coming back around. After all, Bug Spirits were all the rage back when, but they got a long break. Now they get to come back, bit by bit.
From a Player's perspective) They've taken a LOT of hits, and it pays for them to stay out of the spotlight. They lost their founder and a lot of their best minds with the Arcology. Remember, Aniki built the Arc with the dream of self-contained corpo-utopian living in mind. He was a ruthless businessman, but he did have a dream of (by his standards) helping to build a better future. The AEP was only one part of that. He ultimately committed seppuku (in a digital sense) out of shame for all that his dream had been corrupted into being. Japanese megacorps that have a founder or chair of such personal charisma tend to put a lot of stock, pride and face into that leader. They take cues for their own identity from them. Aneki's shame was personal, and most potent of them all, but every Renraku sarariman felt the sting of shame for the failure of the Arcology. It wasn't just a financial hit: it was an ideological disaster. They lost their masterpiece and their father all at once. The people who would have been best-placed to lead from there were dead, or they decided to play things more conservatively. Renraku has the majority of the telecom holdings in Japan (a MAJOR data hub), not to mention assets across the globe. Right now they know it's still too soon to stick their heads out in a bid to be number one, because to many still equate Renraku with Crash 2.0 and the Arc. It's in their best interests to play it quiet and work on their basics. Build their portfolio. Fund R&D. Keep their eyes open, ears to the grindstone, walk softly, and wait for the opportune moment.
As for Shiawase, I've never really seen them as a major player when it comes to the metaplots. Political infighting has always stymied them, time and again. Marriages and inheritances, Imperial relations and Fuchi stock all serve to consistently strain them from within. I'm one of the people who remains shocked they've never gone Fuchi and just split into a bunch of others.
MCT has always struck me as the monolith Japanacorp (their corporate logo certainly supports this), and the one you hear about the least. They are the most... well, stereotypical of a Cyberpunk Zaibatsu. Yakuza connections. Computer tech. Heavy Industry. Traditionalists. The thing that makes them SR-unique is Unit 13, Pentacle Publishing and their other magical pursuits (like their examination of the Elemental Scrolls in the 60s). It might be nice to see them really chase something magical down, other than artifacts. Possibly do some greater investigation of the kaern found under LA- oh, I mean the Deep Lacuna.
