public variables being accessed from outside the class, bad idea?

Nothing wrong with doing either and in fact in most cases it's the simplest way to access other components or components on other gameObjects is just to use public (explicitly as opposed to generally where you want to use a static variable). Especially if you want them accessible in the inspector window. I honestly really don't know what's actually best practice and it doesn't seem to make a whole lot of difference other than it's quicker to simply write "public" if that's all you need.

For things like enumerators etc and evaluating them to a variable then that's typically when I use setters and getters. I've been developing in Unity full time for 5 years and really I still don't know and working with other developers there doesn't seem to be a right or wrong answer and sometimes comes down to personal preference.

I'm a lazy, sloppy coder so I'm probably not good example of best practice but I just do simplest thing of what works. I've never come across an issue or found it to be a big no no in Unity to access public variables (which is normal/most frequent way of exposing to inspector anyway).

I suppose it depends if you're talking of access in terms of write access too, if only Inspector access is required then makes sense to use [serializefield] rather than make public, but since you mention setting and getting then we're talking more than exposing to inspector, and I personally don't see anything wrong with "public" which has dual meaning of exposing to inspector too.

Pretty sure it's considered the basic "normal" way of accessing a variable from another class/component/gameobject within Unity is just to make it public. That's my opinion and I'm sticking to it, lol.