These are very young companies, working with a good that has huge price volatility, resulting in them holding vast amounts of wealth. Ignoring the social, political, and economic debates around bitcoin, these companies have enormous risk and are high profile targets, and have varying ability to protect themselves. All this leads to uncertainty.

So then why don't these Bitcoin companies embrace ridiculous amounts of information disclosure and transparency?

Don't tell me you "take every precaution." Detail what precautions you are taking. Name an external pentesting firm that tests your infrastructure quarterly. Post their findings a few months after you have address the issues. Open Source everything that you can. Offer bug bounties paid in BTC for security issues discovered. Discuss, in detail, your hot/cold wallet storage setup. Do offensive analysis to determine the most likely attack scenarios, and publish them, along with the layer defense you have put in place to mitigate the risk.