Rest less often?
Nothing in the game requires you to take long rests.
I long rest as little as possible even when my main is a mage. (My first long rest is usually at the Druid Grove after I've defeated the Bugbear assassin and the Harpies.
It's your choice.
If you want your Warlock to shine a little brighter only take long rests after every 5 or 6 encounters.
And that is a BS argument, you are essentially saying gimp your other characters to make your warlock seem balanced. That isn't a meaningful choice in terms of gameplay, that is a meta choice on whether or not you want to play with a self imposed handicap. Yeah, you can polish a turd, but it's still a turd no matter how shiny you make it or how much you wish it were something else.
So you are looking for Larian to "gimp your other characters" because you don't have the self control to not rest after every battle?
By making the choice to have your characters take an 8 hour rest after every 3 minutes of combat you are literally meta-gaming each battle.
Starting a battle with less than full resources isn't a handicap -- it's Dungeons and Dragons.
If you are doing something that is diminishing your game-play enjoyment then stop doing it.
To use your own vernacular, you are the one who is bringing the turd. If you don't like how it smells then stop bringing it.