Frameworks exist to make our job easier and build applications easily. There are reasons to pick or not to pick a framework like @gijovarghese has mentioned in his well composed answer.
My personal favorite reason to pick any framework would be to keep your state in sync with the UI, I think that's the core problem a framework solves. Pick a use case - let's say you're building a Social media app. Try thinking about your codebase on pen and paper in Vanilla. Now, repeat the same process, but this time, assume that you're using a framework. I for one believe that the later is a lot simpler to maintain.
" not worry about keeping up with the latest front-end javascript trends" - You may not want to use the latest framework, but you need to keep yourself updated with the latest trends to write code in the best (and if that best is amongst the latest trends, you need to pick it up) way possible. Take ES6 VS ES5 for instance. Variable hoisting used to be a huge problem until ES6 became the standard.
I understand the frustration when people are giving you all sorts of ideas or are marketing their favorite frameworks, but if you do your research today and pick one, you will actually achieve your goal of writing simple and maintainable code. Good luck!