Curses are mechanically flawed in Dungeons & Dragons, but a DM can provide a few tweaks to turn them back to a frightful fantasy experience. Cursed items and magical effects are an age-old fantasy trope, so it's not a surprise that they appear in Dungeons & Dragons in some form. There are a few different types of curses in Dungeons & Dragons, ranging from the Death Curse at the heart of Tomb of Annihilation's plotline to the curse of Lycanthropy to cursed items that can't be un-attuned and come with some sort of negative penalty, to the actual Curse and Hex spells. But with the exception of the Death Curse (which isn't technically a "curse" at all), just about any curse can be removed through the use of the Remove Curse spell, a spell available to Clerics, Wizards, Warlocks, and Paladins. This means that any curse can be easily wiped away by a Level 5 Cleric, Warlock, or Wizard or a Level 9 paladin.
Because a curse can be wiped away pretty easily in Dungeons & Dragons, it robs DMs of a fundamental fantasy storytelling tool. Countless fantasy stories feature curses by witches, hags, evil wizards, demi-gods, and other nefarious magical creatures, and it seems....counter-productive to remove that type of story from any campaign that goes above Level 5. Luckily, there are a few options for how DMs can "buff" their curses to provide players with a bit more of a challenge.
One easy way to make a curse more challenging to remove is to require a specific spell component to negate it. While the Remove Curse does not require material spell components as written, a DM can choose to specify that the nature of a specific curse requires a rare plant or a specific type of gem, which of course requires a quest to obtain. If a DM wants to really draw out a curse storyline, they could require the player to actually find out what spell component is needed by consulting a priest or a magical expert before sending them out on the adventure to find that component.
Another option is to require multiple spells to totally clear a curse away. Perhaps a curse is stubborn enough to require two simultaneous castings of remove curse, which then requires the players to figure out the mechanical "trick" to solving the curse or at least forces the players to act in concert. In previous editions of Dungeons & Dragons, certain curses like mummy's rot required the spells remove curse and remove disease to be cast within a minute of each other to be removed.
Another option is to tweak how curses work to require more potent castings of remove curse. If a curse is inflicted using a 4th level spell slot, a Cleric might have to match or exceed that spell slot, similarly to how counterspell or dispel magic only automatically succeed when they are cast at a spell level equal or below that of the spell they're trying to counter. You may require a spellcaster to make a contested Wisdom, Intelligence, or Charisma check to see if their will exceeds that of the person casting the curse. As the DM, you ultimately can choose how mechanically "crunchy" removing a curse can be, even if that means leaving the curse's fate to the roll of a dice.
Curses are supposed to be scary and dangerous, but it's ultimately up to the DM to decide just how difficult they are to remove. The DM can choose to keep with the rules as written, or they can turn curses into something that even high level parties fear.
Let us know your thoughts on curses in Dungeons & Dragons in the comment section or find me on Twitter at @CHofferCBus to chat all things D&D!