If you don’t need that, great. Many new players have a much easier time learning the rules when it does tell them those things rather than leaving it unsaid.
Many experienced players find the reminder useful, or simply use keywords in rules as a way to more quickly scan and understand something they couldn’t recall from memory, etc.
The eternal tension between two goals that do not always point in the same direction:
1. The core books must teach legitimately brand-new players how to play (that's how the hobby grows, rather than, y'know,
dying out)
2. The core books must be smooth and easy-to-use for old hands who just want to Get Stuff Done and don't want to faff about (which is what the vast majority of people actually
playing the game really need)
It's one reason why IMO there should be a fourth...call it "optional core" book, published after the previous three:
Rules Cyclopedia. A dense, no-nonsense, rigorously organized
reference manual for the game. None of this "gently ease players into play". Fill it to the brim with rules, options, variants, etc. No magic items (except as part of "make your own items" rules, if present). No monsters (except to illustrate "build your own monster" rules). No spells (except as part of "make your own spells" rules, if present). Etc. Cut the chaff, focus on the most important bits. Reduce the internal art content if necessary, though I'd prefer not to do that because art is just...nice to have.
Cut and dried, THE reference manual if you want to Do Xth Edition Things. Re-issue it every (say) 5 years with all errata directly implemented into the text (perhaps leave ample blank space to account for such alterations?) You don't
need to buy the re-issue, it's just more convenient for people just getting in.
Sort of like how one might say that
Lost Mine of Phandelver isn't
technically a core book, but is a relatively well-made adventure and was the very first adventure specifically published for 5e (included in the Starter Set).
This way, the tone and style of the PHB and DMG can be geared specifically for teaching, introducing,
helping the new folks, while the RC and MM can be relatively cut-and-dried, to-the-point reference manuals for folks who want an eminently usable book that won't throw a mess of unnecessary verbiage at them when they just need to answer simple mechanical questions.