Just to add my tuppenceworth in....
My understanding of the frying of spices process is to release the flavour, particularly, the oils in whole seeds. In traditional Indian cuisine, whole spices are often fried, if the seeds are to be left whole in the dish, or fried then removed (cardamom, cloves etc. Another method used is to dry roast whole spices then grind them before adding to the dish (as in the process for making garam masala).
I don't know how commercially sold ground spices are made, but I would assume, with seed-based spice powders, there will be some heating/cooking process invloved before the spices are ground? If that is the case, then the only flavour remaining is in the powder. I'm not sure if frying the powder is going to achieve anything other than, perhaps, flavouring the oil and giving a more even distribution of spice throughout the dish. Or maybe the powder begins to burn and produce a different taste? I don't know.
Hey, I haven't actually answered anything............oh well.......nurse!!!!!!