Your points about CSS are all valid - no problem.
I've added a post requesting discussion of allowed HTML: Additions to Approved HTML.
What I've posted constitutes what I would have proposed; however, as stated in that post, I think concensus across the Monastery is important.
I'll await feedback and then modify as appropriate to form a proposal that most agree on (or can, at least, live with).
As far as syntax-highlighting is concerned, I was really only providing an example contrasting the style element with the style attribute.
The example could just as easily have focussed on some other aspect of styling.
The script I mentioned doesn't operate on Perl, it's just written in Perl; if interested, see
Syntax-highlight Non-Perl Code for HTML.
Given your points about CSS, this is now entirely moot (at least with respect to PerlMonks markup).