Sweet corn is not useless. No vegetable is for the most part.
Sure, it contains "pesky" starch and there is cellulose but that's not the only content and in addition, there is nothing wrong with starch as a part of a balanced diet.
Maize, i.e. corn, is staple food in many places. For good reason, too. It is high in dietary fibre and will keep your baby regular. And it is filled with thiamine - a critical vitamin for healthy cell production, carb metabolism and neurotransmitters. Humans cannot make thiamine and must obtain it from their diet. Thiamine deficiency is a killer. Unsaturated fats are also essential for cellular growth and it is a good source while avoiding a huge amount of saturated fats. It also has about 11% of an adults' daily requirement of iron. Critical in babies (especially BF'ed ones). Your baby needs a high amount of carbs and corn will supply them from complex carbohydrates (starch and other polysaccharides). Better than a hit of sugar.
Honestly, sometimes it seems like bread, corn, pasta and other sources of complex carbohydrates are like feeding your baby coca cola in a bottle. Starch stabilises blood sugar longer term than a hit of sugar (low GI). While little babies don't have a full amylase supply early on, they still have a little (including salivary amylase) and do have the same levels as adults by the time they're 1.
Finally, babies playing with different textures and flavours is critical for physical and intellectual development. If you keep shielding your kids from things you see as useless (which I strongly differ from things like coke, lollies and other unhealthy foods) they're potentially going to be picky eaters.