I'm active in one of the major programming languages in engineering: Matlab and its important toolbox Simulink. Like other tags, which are not directly involved in software development, e.g. R and LabView, they are clearly underrepresented here on SO. Basically because SO is not that known amongst engineers, physicists, etc. - but they are of significant importance for their respective fields.
While I really don't care that in tags like C++ even beginners can earn 10k+ reputation in a fairly short time, and in Matlab just a handful of all-time top users can ever achieve that, it bothers me that I'm not able to share my experience in small tags on Careers 2.0.
I understood what are the requirements for a tag to get the ability to be a top tag, and yes Matlab fulfills the requirements. But Simulink does not, though it is very important for future employers.
So for my opinion there should be exceptions. One should be able to vote for, let's call them major language tags, not to follow the rules linked above. On the other hand it should be possible to vote for exclusions of meaningless tags like matrix, I would be able to include.
Actually there shouldn't be restrictions at all, as like for a real CV everybody should be able to decide for themselves, what tags he wants to show. And if anybody wants to state that they are in the "Top 10% of plot", making the employer asking themselves: "What does he want to tell me with that, is he a printer?" - it should be their choice.