First, I definitely agree that dehydration/rehydration can result in loss of aromatics and flavors. I think it is a great idea to add the flavor/spices after you dehydrate. And, as you mentioned, it's a great way to add variety.

Second, I used to buy a lot of spices from the Indian grocery stores, because the prices are sooo much better. But, I have found that the spices are not as flavorful. It could be due to age or improper handling, but I think its mostly due to diluted product. Whether intentional or due to manufacturing process I think a lot of Indian spices have other things in them.

Lastly by "chickpea mush", I am assuming your are referring to a dish of course mashed chickpeas? If you like it pretty finely mushed, then you could just use Gram/Garbanzo/Chickpea flour and cut out dehydration altogether.