But there are a couple of things that make me personally think software engineering is a misnomer.
Firstly, traditional engineering disciplines are generally pretty black and white. It is applied maths and science. If you build a bridge, you can use physics and maths to pretty much prove that it will handle a particular weight/load and so forth. Software development is rarely like that, and even if you are writing software for an engineer and therefore you could argue that you can prove the calculations the system is generating, it is really the problem domain that is engineering but the way the software is put together is not so easy to prove.
Secondly, I think the term actually does us a disservice. Software development requires intuition, craftsmanship, pragmatism, determination, adaptability, artistry. It also often requires understanding human nature, empathy for users, being able to learn and understand endless problem domains, an eye for the aesthetic. All of these things aren't generally required for traditional engineering disciplines.