Nothing wrong with requiring some repetitive grind to progress, but FFS...

Make it plausible! What''s my character''s motivation? Fighting for a cause, in a war, trying to survive, etc, or just killing everything for no logical reason?

Make alternative approaches to progress. e.g. variations of combat, crafting, exploration, and social mechanics. Not just mobs to kill all day long.

Don''t make levelling the entire point of the game. Do these characters exist just to level, or is that more of a side effect to participating in the gameworld, persuing other goals?