I really have no idea what it is about the rules presentation that cause such behavior - and it's puzzling.
While I can do what you do and ignore silly things within the rules as though they are the end all be all of what can be done, others see the mountains of rules and think it provides the best "balance" to just go with what is there.
I have a few miniature games and other types of combat based board games that have rules that look not too different from the 4th edition books in style of presentation.
Axis and Allies comes to mind. It just seems the 4th edition books are a bit dry.
Maybe there is just too much little things to track, but most playing it for a while now should have those little things down.
It really does give the feel of a miniature wargame with how it is presented, not only words and focus, but design.
We could play what if all day long about those you play with, but have you asked them, why they dont try things like you do, or the DM to see if it fits with him?
If not entirely new players, then getting more insight on why they are only using "options" from their character sheet might help all to understand what it is that is causing it. That would be the most helpful thing, for yourself and its inclusion in this thread as accounts of it happening, why they are only pulling things from the character sheet, rather than trying new things.
I would like to hear, if they offer an answer, at least.