Sadly, not many know the true meaning of the Highborne aka Quel’dorei.
People tend to believe that having golden eyes, having arcane powers, and having golden jewelry makes you a Highborne, however a Kal’dorei without Highborne blood — such as Illidan Stormrage - could master arcane power if he so wished (and had access to it). In fact, the mastering of the arcane arts was common among the populace, resulting in organizations such as the Moon Guard, the official military sorcerers.
The Eldre’thallasian Highborne who have joined the Kaldorei Resistance have lost their title of Highborne by obeying to the rules of the lowborne, they are no longer respected as it was in the times of the Empire, at the moment their purpose is to teach the young Kal’dorei the ways of Arcane, but nothing more. Moreover, being a Nightelf magi, does not mean you are a Highborne neither, you are one of those young Kal’dorei who is learning the ways of the Arcane.
People need to understand, that being an arcane mage does not make you a Highborne, it is something that passes by tradition, by blood just like the Shal’dorei say:
Quel’vala thonos- Nobility through tradition.
The Kal’dorei should accept the fact that the Shal’dorei is the definition of the Highborne, and move on. As the Shal’dorei are the only elven race, besides the Sin’dorei who kept true to their traditions, and nobility.
The Shal’dorei might not look like their Kal’dorei cousins, however, the Shal’dorei are the ones who the Highborne of the Empire would have become eventually, meaning arcane infusions and etc.
Suramar still has the division of the Highborne and the Lowborne, in the conversation below, which can be found in Court of Stars, proofs it.
Spellblade Aluriel says: Lowborn filths! Perhaps reducing their rations of arcwine will remind them who it is they serve.
Haughty Aristocrat says: I simply can’t fathom why some citizens resist the Grand Magistrix’s plan.
Spellblade Aluriel says: As their hunger grows, the rebels will turn on each other like starved rats. Any sympathizers will be exposed and order will be restored!
Aluriel implies to the non-noble citizens as lowborns.
That being said, playing as a Shal’dorei, you are the one to decide if you are coming from the noble family, or from the commoner family.
(Sorry for the wall of text, been late to party)