D_E
Explorer
Additionally, even many of the tougher/more singular monsters are relegated to either slapping spellcasting ability on it ('cause that never gets old, right?), or having it be a passive ability such as a medusa/basilisk stone gaze or the rakshasa's cursed claws. The number of creatures with a genuinely unique active abilities is annoyingly small. Even other kinds of passive abilities, like auras, are strangely absent.
Just want to point out that, in many cases, monsters with innate spellcasting have a very limited number of spells that are chosen to according to the monster's theme. The idea seems to be that whenever possible they re-use an existing spell, rather than writing a bunch of unique abilities that are all similar-to-but-different-than the spell (and each-other).
I'm not sure which is better, I think 4e put a greater emphasis on having everything needed to run a monster in the monster's stat block, while 5e is putting a greater emphasis on conformity across monsters.