Feedback I've got so far:
1) "Many people (don't know any %) switch off Java (and Java script?), since they are concerned that they open up a loophole for malware and ad/spyware." From the discussion I had with one user I gather that they feel the Java sandbox is "too open" (e.g. access to files on the users computer) and it is unreasonable to expect someone to audit all that code in the applet for any hidden attacks. 2) "Some browsers do not come with Java applet support enabled or even included." I have not found one instance of this, yet, but I'm sure this is true. It is, however, not clear to me, what percentage of users would fall into this category. My guess is in the single digits, really.
Please add to the above list, if I missed something or you have not chimed in, yet.
Here is a short discussion of these points from my current point of view. 1) It's a dangerous world out there, yes. One can never be too secure when stepping out into the Internet. However, would you trust someone like Wikimedia to send you non-evil applets, in case there is a reasonable and enforced way how Java code becomes an applet served by these servers? One needs to discuss whether such way can be practical, sure. But if it exists, do you really insist that *still* it may not be allowed? 2) So, if a user wants to work on a lab (= interactive lesson) in Wikiversity, do you really expect *no* additional software (plugin) should be needed? That sounds like quite a limitation, does it not? If this is true and we want to avoid those limits, then we should choose the most widely available tool, that can do the job, fits the necessary license requirements, and does not create an unreasonable burden to make it work. Why would an applet not be one of the top choices?
I think the only serious problem to address is the trust/audit issues with applets. We need an open and trustworthy process for how applets are made and delivered. That does not sound impossible to me...
Andreas =:-)