Korthia is literally right there and provides a 233 item level, 6 item levels under heroic. Why thoes 6 item levels weren't just given? I don't know. But lets not act like there isn't a casual way currently in WoW to increase your characters power.
The bigger issue IMO isn't the gear or even the activities. The first issue is a fresh max level character takes too long to get the ball rolling. Between covenants, soulbinds, legendary crafting, and storylines there's a ton of stuff a character has to do to start rolling.
Legion, a very successful expansion by most memories, was almost universally despiesd until the final patch where everything to get the character rolling was completed almost instantly.
The second issue is that unless your watching sims, raid reports, and checking things like io its hard to feel your character progressing. World scaling has made it so that you feel like your jogging in place despite gaining gear and power. My current character is 249 (could go to 251, but poor luck with dom socket pieces), yet I still have to wait around for several rare mobs in Korthia for others to lend a hand.
In prior expansions like MoP with the Isle of Thunder, once I was around the ilevel cap I could 1 shot mobs and never bat an eye at attacking a rare.
The issue isn't gear, and it isn't activities. Its the lack of feeling of progression outside of an analytical standpoint and the fact there's a lot for a new character to start being viable in any content outside of world content.