I love talking, dealing with and of course eating all types of food, so the idea appeals to me. Enriching the cooking activities in DF using a variety of ingredients, cooking methods and recipes would add a lot of fun.
However, I think the main problem with food right now is that it does little except create wealth, make people happy and provide a few benefits in storing the food. I know that actually sounds pretty cruel: what do I have against making dwarves happy? The problem is that there are already tons and tons of other ways of generating wealth already, the food is way too expensive, and there are also many other ways of making dwarves happy. This means there are few consequences to not bothering about cooking, making the whole endeavor less fun. Cooked food should have a value in itself.
It's more fun if you have to create a variety of different foods because you have different pressures to do so. An earlier post suggested that nobles hold dinner parties requiring certain types of food. I think that's the sort of challenge that would make creating a varied cuisine a much more interesting task than it is now.
Besides complicated desires, another reason why food varies so much is because our bodies need different nutrients. Maybe it would add a nice level of challenge and complexity to have dwarves require different nutrients from different types of food, instead of just booze + any kind of food. Having this need arise in the gameplay would force players to pay more attention to what types of food they stock, and perhaps to come up with creative ways of implementing them. This of course supposes greater control over the kitchen workshop, but I think that's coming in a later version already (for all workshops).