So imho stealing from the ground would be a problem since pretty much any thief is capable of taking anything they want even with 150-200 skill which is not that hard to get. Also what should be the fail formula? Who to check it with? Items are just lying there so it should be easier to steal them than from regular npc/pc = even less steal skill required = nothing solved...Either make some magic so picking up a 10mm pistol will make insane amount of noise that will cancel your sneak or I dunno. Its not that cool solution imho.
Yes you've got some points about that, but I believe it is possible to make a formula that will make impossible to have 300-330 sneak and being able to steal all or most things from the ground with 150-200 steal skill. Remember that in case you are detected and killed, you risk nothing - most likely you came there as bluesuit, without items and you will not risk any reputation loss.