well not really
what if you have a standard banner with links on that and a sidebar with links there. Do you really want both looking the same, same background, same text, same size, same hover even (i dont ilike variety)
besides 2-3 types of "a" classes I think are fine as long as they are in certain spots where people expect links, TOP, LEFT, BOTTOM and even sometimes RIGHT
Not to mention any link in text should be underlined our somehow highlighted to stand out.
Having multiple classes doesnt distract from the usability of your site as long as you are clear and consistent. Besides it adds some flava and also makes for better and cleaner websites. [Hammer]
Nike Failed Slogans -- "Just Don't Do It!"