I am, too, but I feel its important to consider how much work comes along with adding an entirely new form of gameplay that can circumvent the current forms of combat.
True, balancing does come into effect. But most of that comes down to number tweaking and some extra scripting, even with the system already in place.
NPCs could detect poison based on their alchemy skill, combined with a luck factor. Also, specific categories of ingredient could be easier or harder to detect poison within. Unusual scents, different coloration, etc, etc.
Successful death-causing poisons could require high-level player alchemy checks, whereas unwittingly-created lower-level poisons would act as a lesser-effect poison that would leave its victim alive and able arouse suspicion. Further, NPC endurance should have an active role regarding how well they resist the effects of the poison.
Guards could have specific AI packages designed to have them search players (and other NPCs) in the event of poisonings or attempted poisonings, and if the player has any poisoned food, they would be implicated. Multiple poisonings would increase the frequency and radius of that search.
If the player is smart and ditches or uses up all their poisoned ingredients, then perhaps there could be a special alchemy-skilled member of the Legion. If they are the ones to search you (and they'd be rare), then they'd be able to identify poisonous residues on your equipment and implicate you.