Batteries are getting lighter as tech improves. Each time battery density improves the amount of energy increases, but the weight doesn't. Can get either longer range or lighter vehicle with improved battery tech. I don't notice ill effects of a heavy vehicle. I do notice positive effects of a low center of gravity. My Model 3 takes turns like something amazing, and have yet to hear the tires squeal.... bigger battery makes your car A LOT heavier ALL the time.
Someone has estimated that battery density improves 5% a year. Here are some numbers of increased range without heavier batteries making assumption of 5% energy density improvement per year.