Remember that Rand would have had subconcious access to LTT even then, so the traps may have been dangerous even to an AoL'er. And Demandred doesn't like risks.

Of course, Be'lal failure to raid the stash is a glaring plot hole, though it always possible that he simply made a silly assumption that because Channeling was 'outlawed' in Tear, they wouldn't have any such objects. Or perhaps he actually already took another angreal from there (which would have been lost after he was BF'ed.

On the one hand, I hate having to justify plot holes, but on the flip side I also generally prefer authors that let their readers fill in blanks that aren't really that critical to the plot.

I mean in LotR, what would have stopped Gandalf from just flying one of the Eagles in to Morder and dropping the ring into Mt Doom? No riskier than using hobbits. I'm sure there are reasons why this wouldn't have worked, but I don't think that books always have to explicitly say why characters made bad decisions or why other occurrences happened.