Well, there are two things wrong with that. For one thing, you do not lose beauty when you use it to your advantage, so it is not an opportunity cost. The second and more important point is that you should write to communicate as effectively as possible: This means using jargon ONLY when it is actually appropriate, not whenever you feel like you can sort of fit it in.

I suspect that the tendency of people here to overuse jargon is a large part of what makes people consider Less Wrong cultish. Honestly, I feel someone should compile a list of Less Wrong "DOs and DON'Ts", which includes rules like "Don't use the word rationality as synonym for smart or good or other more specific words."

(The above should not be taken as further criticism of Swimmer specifically)