> why the BankID "detector applet" wanted full access to the host system
It tries to detect presence of common malware and to fingerprint the system so in case of an infection it would be possible to black-list the customer's PC until Windows is reinstalled. In any case, running strace against browser displaying a page with BankID is rather entertaining.
> They were influenced enough to make it work only with a single vendor's technology
If banks would now about the amount of support calls they would receive about banking site not working on IPad, BankID would be dead on arrival. And banks could easily predict that state of affairs by trying to run BankId at the moment it appears on Linux and other non-mainstream systems with browser installed. That is, BankId has not even been a cross-platform solution. Indeed, those "were influenced enough"...