I signed up as a beta user some time ago. I haven't done much with it, I'm afraid.
My goal -- others obviously have different workflows -- is to take a "parts list" exported from Kicad and import it into something which will generate a proper BOM. I don't see the point of polluting the schematic with extra pricing and other data.
That sounds great. The missing link is a "company part number." That's the link between the components on the schematic and the components maintained in the database. The database will have manufacturer, manufacturer part number, cost, data sheet links, etc.
The only things the board parts list (as generated from EESchema) really needs to have, for each component in the design, are:
a) "company" part number, which is the key into the data base,
b) reference designator
c) part value (vital for passives like resistors, less so for op-amps and FPGAs)
The BOM generator (outside of Kicad) takes those three things in and looks them up in the parts database, and spits out a BOM with a line for each distinct component:
a) Company part number
d) Manufacturer part number
e) List of reference designators
Things can get a little more interesting when you consider that you might need to order parts for a "production run" (defined as "building more than one article"). This is because of price breaks per quantity. So you might wish to add a "Number of Boards to Build" option, which is a simple multiplier of all the individual parts quantities. Then the BOM processor can look up prices with the correct price breaks and add them to the final BOM against which parts are ordered.
A second complication is that the BOM processor should take into account quantity of parts on hand, so that the "ordering" BOM doesn't include parts you already have.