Giving your dog a variety of foods, and making their diet exciting for them is important, and while dogs will pretty much eat anything that's edible (and some things that aren't!) You have to try and give them a mixture of foods and not just give them things you know they like.
A dog's nutrition is important and just like our own diets, we have to make sure they're getting the essential vitamins and minerals they need to keep them healthy. If they only eat what they like, rather than what's good for them, then aswell as ending up being overweight, it can affect their digestion aswell as their mouth, teeth and gums.
There's a lot to think about when owning a pet and especially a dog, and while I think most people only think about things like talking it for walks and the love, affection and company they give you, you also need to think about other aspects aswell.