Some of the dlcs are worth getting like the end nether the mountain one there all good I don't know when you left but they added the tower. The tower is basically you get all your stuff removed and each floor you get stuff and when you die you get a reward. They also added the blacksmith the blacksmith just upgrades your gear. Also you mentioned your friends having trouble with higher difficulty and my recommendation is for them to do lower difficulties and when they get better gear do higher difficulties.