I find the spring model of the attractive Coulomb force alarming. Most springs that students are familiar with pull harder the more you stretch them, and, if you stretch them far enough they break. The Coulomb interaction is not like that. It seems terribly confusing to model the attractive Coulomb interaction with springs. It seems it would be better to get students to play around with charged objects until they get so familiar with the Coulomb interaction that it becomes one of the things they use to model other stuff with, rather than using springs to model it.