Before the game was adjusted to help players level (not big adjustments but things like luck, powerleveling, pet glitches, etc) the level 17 quests were the turning point in every character. You gained roughly 1.5 levels, got most of the coaches, and most importantly — got an entire set of class specific armor.
The armor was colored, boosted needed stats, and was the first taste of filling your classes role. Some people wore this armor well into the 30’s.
Eventually players began using their higher level mains to collect the items and trade them to their alts. Further, as characters began leveling faster and crafted armor had much higher durability, the 17 quests were phased out. Why run to Halas when you really didn’t need to?
In the rush to move to the endgame and the boredom that people began to find in running around the map, over and over, phased out the level 17 armor quests.