There is no reason not to. There namespace already defines them as subjectives, so there is no point in adding a Justifying Edit to tell that some people disagree about this trope.
And valuable extra information should be worked into the original bullet points, simply because that is more readable, it has nothing to do with the namespace. (Well, 
and 
are the exceptions, but that's different.)
Hey, my philosophy has always been that a Subjective Trope is...well, subjective. It's assumed that the reader will disagree with what's written, so there's no need to record disagreement on the page. But my beliefs are not always the site's beliefs (oh, spoiler tags), so I wanted to find out for sure.
|Y| = |X| Add 5
Yes. <Dalek>Eliminate natter.</Dalek>
Goal: Clear, Concise and Witty
Excellent.
What is our policy on Natter in the YMMV sub-section of works pages? Do we accept it as the price of doing business with a series of subjective tropes, or do we hold the YMMV tabs to the same Natter standards as the regular works pages?