The lack of a style attribute was also my first thought; however, on reflection, it's really a lack of a style element that's the (bigger) problem.

To elaborate on that, I have a script which generates HTML containing syntax-highlighted code, that looks something like this:

<pre class="syntax-highlight">
    ...
    <span class="variable">x</span> <span class="operator">=</span> <s
+pan class="string">...
    ...
</pre>
[download]

While I wouldn't want to change, for example, every <span class="string"> instance to, say, <span style="color: #00ff00; background-color: #000000">; I might like to add one simple block like:

<style>
...
pre.syntax-highlight > span.string {
    color:            #00ff00;
    background-color: #000000;
}
...
</style>
[download]

However, beyond that, which really just shifts the focus of where style is missing from, I do agree with you. id is not an allowed attribute for any allowed element; the lang and dir attributes are only allowed with the blockquote element; and so on.

There may be reasons why things are this way. Perhaps someone from pmdev could provide some feedback.