I also wanted to write that the topics didn't spark my interest, but I don't know if I should include that.
In my opinion, you should absolutely, positively not include that. Law school is often incredibly boring, and you will be expected to devote huge amounts of time to learning very dry subjects like civ pro, property, and wills & trusts. Trust me, most of the topics in law school won't spark your interest either, and the admissions committee knows this. The best possible way to overcome a 2.74 GPA is not with an addendum, but with a high LSAT score.
If your LSAT is sufficiently high, the addendum won't even be necessary.
Any addendum that you write will only be a small factor in the admissions process, and will probably only get glanced over. Those types of things are often most useful as tie breakers, assuming that you're on the cusp of admit/no admit. Law school admission is a numbers game, and if your GPA is below a school's median then you need a higher than average LSAT to compensate. If you don't have an LSAT score yet, start studying and get as much prep as possible. For the purposes of law school admission a 2.74 is relatively low, but it's not fatal. You can still get into plenty of good schools if you score high on the LSAT.
If you're still in college, try to take classes that will allow you to maximize your GPA. Law schools don't seem to care about the content of classes too much, just the grades. If you do end up writing an addendum, just be entirely honest. Explain that you had to work during college, and that you've learned from that experience how to better manage your time and priorities.
Do you know which schools you're interested in?