All Item Level 100+ items are getting a boost soon which will help to close the gap a tiny bit.
Content is equally accessable to all players, the difference between hardcore and casual players has merely become more visible. Why is this a bad thing? Why is it bad that people who devote more time and energy to the game have something to show for it? Does it detract from your ability to play the game if the game has people who are stronger than you in it?
Extremely casual players have reives, quests, new jobs, coalition assignments, mog gardens, and soon monstrosity. Slightly less casual players have skirmish, pick-up delve, and WK reives. Hardcore players have delve NMs and megaboss.
No matter how casual or hardcore you are, this expansion has given you some avenue of advancement for your character. So why do you look at the hardcore players, covet the things they earned by devoting themselves to the game, and think you should have it for a fraction of effort? Why are you incapable of just enjoying the content which was designed specifically for your level of play?