I'm talking about table 7-3: on p. 216 of the DMG.
Anyone notice that the table has results of 61-00 for magical Full Plate. I can't fathom the reasoning behind this. Why in the world is 40% of all magic armour in existance Full Plate? Why is only 1% of the magical armour leather, or splint mail?
I'd have assumed either a table that gives roughly equal chances of finding any kind of magical armour or one that makes magical full plate rarer then Chainmail. One that makes magic full plate really really common in comparison to almost all other types of armour which are usually exceedingly rare. There are a few other armours that have around a 10% of being found and mostly they seem fine - though I'd like to know who's skinning all these bears or whatever to mass produce magic hide as well. Must be some kind of Druid sweat shop.
I don't know if this is the logic or not, but as far as the classes go, Fighters, Paladins, and Clerics can all wear full plate armor. Once you figure in the cost to enchant a suit of armor, what kind of armor usually isn't a limiting factor toward what you are going to enchant. Wizards can't wear armor normally, so they are going to make whatever their "customers" want, and clerics are likely making armor for themselves or their allies (fighters, paladins), so perhaps that is why it skews toward plate armor.
This may also not be much in the way of logic, but full plate armour is the armor of the wealthy and prestigious in medieval European cultures. Any knight who could afford a suit of full plate would get one over a suit of chain anyday. The same would be true of a typical D&D setting. The experienced cleric, fighter, or paladin would buy a suit of magical full plate over a suit of magical chain or splint mail at least 4 times out of 10.
You could also say that since dwarves are the default best crafters of armour, and love heavy armour they would make more suits of magical plate than any other armour type.
Of course the table can be changed depending on what sort of campaign you were playing. A persian desert-style campaign would not have many suits of magical plate at all, and a stone age campaign would not have any suits of magical full plate period. You can also change the table any way you see fit. You dont like the percentages, simply exchange the full plate listing with one of the other armour types.