I like the idea, as long as it is sufficiently random and not only one or two pieces in one or two spots ("oh so it's not in the basement, then it must be in the crypt"). I agree with the_fish that it would be simple to make it an optional feature since computers generally use pseudo random number generators*.

I think the suggested idea might work nicely. Level designers would get a special object, a loot point (not visible to the player of course) to place on maps. Each spot could have a simple list of possible loot with the associated chance of occurring in percent.

One could even extend the idea a bit. Loot in the lists could be arranged relative to a loot spot so you could arrange items that belong together logically (eg sets of plates and cups and silverware). Instead of a simple loot-table there could be a loot tree-structure so that you could have a nightstand on which it might appear either an expensive vinebottle and a cup, or spectacles, but never all three at the same time and never a bottle without a cup and so on.

Standard furniture could have default loot points assigned, so that the only thing the level designer has to do is place some furniture in a room and loot would automagically (and logically) appear on that furniture (eg a winerack might have a set of points where different wines might appear). Then the level designer would only have to tweak the values a bit to his liking if at all necessary.

It would mean more work for the programmers, but less work for the level designers.
* [Optional reading] Not everyone might be familiar with the concept of pseudo random number generators so: Computers are very deterministic in nature, it's difficult--if not impossible--to generate true randomness on a computer unless it has hardware specially made for this task (which most computers don't.) A function generating randomness would work kind of like a dice, each time it's activated it would randomly return a number within some interval (eg 1 to 6). Since the computer can't generate true randomness it uses a pseudo random number generator (which appear random enough for most purposes). That's usually implemented as a "dice function" as well, but it has to be initialized with a seed value before it's used. It then returns a series of numbers (within an interval) that looks sufficiently random. The interesting part is that it will always generate exactly the same series of numbers if it's given the same seed value. Thus if every level has a predefined default seed value that stays the same unless the user chose the random loot option, the loot would always appear on the same spot. If the user chose the random loot option, the current time and date would be selected as seed value instead and the loot would appear on different spots every new second...
Hope it wasn't to confusing.