I suspect it is because we never get the spices right. We went to an indian cooking class many years ago, and the woman who taught it hand ground all the spices herself. The results were amazing, but who has the time?
If you had a service that coupled premixed spices with recipes that use them, that would have been really exciting to me.
We can already buy various pre-made pastes/mixes at the grocery store, but they are really unhealthy.
If we could get the spices, then have control of all the fresh ingredients (meats, veggies) and also all the unhealthy ingredients (salt, anything with fat, etc), that would be attractive to me.
I know that is not what you are doing, but just for the future (a) spices are cheaper to mail and shelf-stable (b) the spice mix is probably the secret sauce of what makes it taste good, and it is difficult to duplicate in my experience (c) leaving the other ingredients out would allow home users to follow either a healthy recipe (fat free yogurt) or special occasion recipe (heavy cream!)
Anyway, FWIW, when I read the first lines of your description, that is what I was hoping for.