Who the heck am I to say whether a particular word or phrase in the text is "relevant"? -- I say, leave it up to the reader. If they are interested in clicking, they can click. If not, the linked page isn't going to jump onto their screen by itself.
I admit that some of this advice has more relevance on a system where a link in one direction always causes a link in the other, and that Wikipedia is not such a system, but when most encyclopedias cross-reference, they cross-reference to related articles. And perhaps some of this is just a "liberal vs. conservative" difference.
I do take VERY, VERY (gee, am I shouting?) issue with the comparison of Wikipedia to Everything2. Everything2 is, in my opinion (and in the words of another Wikipedian) a random collection of crap. Wikipedia at least aspires to be neither random nor crap. That's all I wanted to say. :-) --LMS