It's nice they're so honest about what's in the food, shame it's all fillers.

To put it in perspective a bit, if someone took an average human meal, added an unnecessary amount of wheat/rice/corn (take your pick), mashed it all up together, dried it out and formed it into biscuit shapes, sprayed it with artificial vitamins and minerals, possibly a few colourants and preservatives, then you had to eat it day in day out for the rest of your life, would you get bored?

Look into BARF / raw feeding if you really want your dogs to be happy with their food.