That is a very nice theory. I, too, have a theory, I might as well share it here, instead of making a new thread

My theory:
In my experience of playing Japanese Conquer Online and North American Servers, along with ideas from fellow e*PvPers, I have come to believe that those 'random numbers' are slightly less random, but, still random. That may have confused you, but I will try to explain.
It has to do with the amount of people on the map. In your theory, you talked about the numbers 1-1,000,000, so I will use those numbers as well. Say there are 100 people on the map. TQ Would have to assume that all those 100 people are killing monsters, trying to socket weapons, or in some way attempting to 'roll the dice'. If this is so, in order to help protect the economy, they must figure in the amount of people that are playing. So, with an increase of people playing, there is a decrease in chance to obtain a higher quality item.
Think of it as supply and demand. If there are 500 people playing on the same map, there is a higher amount of items being dropped, and a higher chance to get a met/db, etc. So, to balance this they make the odds change to have roughly the same amount of special items, or a high 'roll of the dice', as if there was 5 people.
Now, i previously stated about comparing to supply and demand. What I meant by this was that if they did not balance the equation, then there would be an abundance of special items in the market. This can go in one of two ways, or, both:[*]Prices would increase, assuming that not all of the 100 people were actually hunting or 'rolling the dice', damaging the other's ability to get better items. This would ultimately lower the amount of items in the market that were above average quality.[*]Prices would decrease tremendously, with such an abundance of special items, the demand for them would become minimal, thus to sell anything they must lower the prices.
Both outcomes have their advantages and disadvantages, with the first being a low quality server and the second resulting in a unfriendly environment of suped up characters.
I knw i seem to jump around a bit in my writing, but if you have made it this far then that is great

Back to the 1-1,000,000 thing. This number would increase by the total people on the map, not the total people on the server. Now, I do not know this equation, nor do I know that it even exists, but I would have to assume that it went something somewhat similar to this:
chanceToGetHighRoll=
rand(1,1000000)/(numberOfPeopleOnMap
/10)
Now I will attempt to explain this equation. First off, I will explain the italic. 'rand' is meant to mean 'Random', and the '1,1000000' is meant to show that it will choose a random number between one and one million.
The bolded number is just to show that the numberOfPeople variable must be lowered in some way, the actual number that this equation would use is more than likely different, but is just an example to show that it must be lowered in some way, or the chances would be extremely low for people to get anything nice. The number of people on the map must be checked to ensure that the number of people on map variable does not go below 1. This can be more easily added by having a snippet of code check if the variable is lower than 1, and if so, making that number 1. So remember that when you see these next equations.
So here is an experiment that I conducted to attempt to explain this in more detail.
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------------------------------------Experiment---------------------------------------------------------------
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Highest Random Number=1,000,000
Random number 1=448,639
Random number 2=693,417
*Max amount of people in map=2,000
Lowest Possible people on map=1
Random amount of people on map 1=500
Random amount of people on map 2=27
In these circumstances, what would be the outcome if there was only one person on the map?
chanceToGetHighRoll=1,000,000/(1)
//remember that the number will be checked, and set to 1 if it is less than 1.
chanceToGetHighRoll=1,000,000
This would then become the highest possible answer that one could get.
chanceToGetHighRoll=448,639/(1)
chanceToGetHighRoll=448,639
As yo can see, one would benefit, in this theory, by being the only one on the map. Since he/she would have all the 'luck' to his/herself.
chanceToGetHighRoll=1,000,000/(500/10)
chanceToGetHighRoll=1,000,000/(50)
chanceToGetHighRoll=20,000
This would be the most you could get if there were 500 people on the same map as you. I do not know how many people are on maps at any given time, but in my opinion 500 is quite a lot. Which is why I made 2,000 as the most.
chanceToGetHighRoll=1,000,000/(2,000/10)
chanceToGetHighRoll=1,000,000/(200)
chanceToGetHighRoll=5,000
So, if the server had a map that was packed with 2,000 people on it, then that would be the highest score possible.
chanceToGetHighRoll=448,639/(27/10)
chanceToGetHighRoll=448,639/(2.7)
chanceToGetHighRoll=16,618
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------------------------------------------------End of Experiment-----------------------------------------------------------------
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I did not include what score will get you what item, because I don't know how that would be worked out. In fact, since the equations that I showed were not what I actually believe to be the truth, if this theory was correct, they are merely examples to show the 'big idea'.
If you read of of that then thank you very much for reading

And even if you didn't, you must have at least read this paragraph, otherwise you wouldn't have known that I was thanking you in the first place:P Criticize as you wish, none of this was meant to be concrete, so it will not bother me.
Ah yes, and lucky time, it would merely add to 'chanceToGetHighRoll' after it had been generated.