One thing I’ve always thought was MASSIVELY important for the “feel” of a guitar is a correctly cut nut. This has also been borne out during my guitar tech classes. Once the student has watched me cut the nut, and given them the guitar back twenty minutes later, they often can’t believe how much of a positive difference it makes.
Typically, guitars come out of the factory with the nut slots not being deep enough. Far too much clearance over the first fret, when in reality the string JUST needs to clear the first fret by enough so that it doesn’t rattle when playing the open string.
Once the nut slots are deepened, the action is lowered at the nut end of the neck, and this improves the guitar in a few ways. Firstly, it makes the open type chords much easier to fret, as you need less finger pressure to do so. It also improves the intonation of these chords, because you’re having to stretch the strings less to push them down on to the frets.
Also, when I’m increasing the depth of the slots, i’m also making sure that they are the correct width, and are at the correct angle. Once finished, they are then lubricated too. This means that the string can glide through the slot without friction during tuning, or when string bending (bending a string will pull it through the nut a little bit). A friction free nut offers much better tuning stability (usually attributed, wrongly, to the machine heads themselves).
So as you can see, it’s pretty important for the feel, ease of playing AND functionality of a guitar. The downside for the hobbyist is that to do the job properly you need nut files that are typically over £100 a set – and you’ll need at least two sets to cover different types of guitars. As you can imagine, this isn’t an amount that most would want to spend, but unlike other tools and things you need to fix guitars, there isn’t a cheaper option that will do the job properly.
I sort the nut on every setup I do.