The idea is that instead of using single blocks for crafting/chemistry/whatever, you use quantities. So if you wanted to make a sword, you might use 4 kilograms of steel, or 3.5 kilograms. The sword might be different based on this, so if you had used more steel to make it, it'd be longer (depending on the volume of the material), slower, and heavier hitting, or vice versa if you used less, and eventually becoming unwieldible if you use too much or uncraftible if you use too little (again, depending on the volume). Also, you prepare materials such as iron by crafting blocks, but depending on the purity of the block you could end up with slightly more or less than average. Possibly altering the base statistics of a material by combining different ratios of the materials used to make it?
This is an interesting idea, but as Starbound seems to already be based on blocks, I don't think that your idea would fit well with this game. It also would likely, if it were compatible with the game style that is being used, be incredibly difficult to code. I'm not a coder myself, but the whole volume and it determining certain attributes of the item might be a bit complicated. The items are already stated as being procedurally generated, so the stats are random, not dependant on how much of a material you use.
This would only deal with crafted items (unless those are procedurally generated as well) . Also, it probably wouldn't be too hard to code, as you could simply take the percentage (or fractional) difference between the maximum and minimum quantities and have that run through different functions for each stat to determine what the changes would be depending on the weapon. Easy to have it sharply increase near either side of the value, as you could simply switch to a quadratic equation when you go past a certain point on the graph... EDIT: Also, this is only the materials, so you convert blocks to the materials, then possibly changing them back to blocks.
Any idea if this is going to be like the modifiers in Terraria? That'd allow this to work, as then they'd be using base statistics for each item that are being randomly increased or decreased, since this would modify that, then be effected by the random modifier.
Sorry, I only know what the devs said but if there is more information given, then perhaps we can say more concretely whether this will work.
I've already started a thread in the FAQ section of the site, hopefully I'll get a concrete answer. It's here, if you want to see it for yourself.
I think we should stick to whole numbers as that is the very point of the unitless system. It allows the player to easily add up quantities of materials without considering fractions to multiply. The weapons are procedurally made too, but you can customize their look.