Everything should try do some basic syntax highlighting IMO. Not too much, or it just becomes a sea of formatting that doesn't help at all. It is surprising how much difference just a little splash of colour can make if it isn't overdone. If possible, always include configuration options for the user though, so those with colour-blindness issues can tweak things to their needs, those who are just fussy can make the o…
If it isn't possible to turn any syntax highlighting an the like off, I will personally look for alternatives.
Not reconfigure individual settings, turn off syntax highlighting all together.
It's not about style for me, it's about readability.