Yeah, I hate it too. I think it has the potential to be frustratingly confunsing to a new player.
Potential, but the non-new player is really the one most likely to be confused. They don't have the same preconceptions of "core" that some experienced players do.
A good friend of mine taught me that before you have an argument that you define your terms. Nothing is as pointless as arguing for hours and realizing you both agree but were using different definitions for the same word.
In this case, there are plenty of definitions possible for "core" from an RPG POV. I have heard it used for the bare minimum books required to play an RPG. I have heard it used only for books that have all that's needed to play an RPG (in which case D&D has no core books outside of BD&D). I have heard it used for books that aren't tied to a specific campaign setting.
Any of these definitions are used and assuming that you are both using the same definition is asking for confusion. An experienced player may get in the habit of one definition because his circle use just that definition. A new player won't be tainted by that experience. He may think one definition is more likely than another, but he won't assume.
In fact, if he went to the D&D website and looked at "core" products he would see many more than just the PHB I (and would have since at least 3.5).
Another "very minor thing" that I absolutely hate everytime I read is the PHB sections on "what you need to play", and they list D&D miniatures there. I hate this so much, because when I started playing, back at 2001 (I think) with the original d20 Star Wars core rulebook (yeah, talk about unortodox start), I had absolutely NO idea how to play the game, and I remember to be very confused by the fact that all I needed was one single book and some dice. But there it was, in the "what you need to play" section, that was it.
Now, someone with the same knowledge I read there would read and ask for the miniatures price on the store, and be VERY confused on the booster model of business. And I can tell you that, if that was me, I would never look at RPG again because of how expensive it was. I didn't have a friend who played for years to tell me "don't worry, it's only marketing".
Of course, today said person wouldn't even open the book, probably, because they would be confused and outraged at how many "core" books you need to play.
So yeah, it might be a minor thing, but I hate it, because I'm sure it would have driven me away if it was like that when I picked up my first rpg book.[/QUOTE]