Understood in both points, and thanks for bringing up the ghoul part, did forget about that.
But bare with me here. The morale of this, is thus...the constance perception of the message.
Seeing what is said (supposedly) about the 'sleeping' factor on Elves. Is one thing. But then seeing something else stated, (likely opposite to that first message), seems totally opposite in meaning.
Likely, that can lead to confusion.
We the older breed, know the differences, but to someone who is not old, and may be just barely new to the material. Will note the 'confliction' and asked the necessary questions to get clarity.
As seen thoughtout this thread, everyone has different take on it, me...I just advanced it to the next level. On a possible scenario that will lead to that 'change'.
I have noted that for a while now, even to the point, in the past splat books on the races, 3rd Ed or 3.5 ED, at one point, they reduce the birthrate to human time, 9 months, instead of 2 years (yeah, FR reference, or older edition).
But that is beside the point, the overall message that needs to said, that if you put such changes on a race's specific function (their natural abilities), but don't put the explaination on why.
Then have another section of texts, that implies that they still do 'retain' that not mentioned natural ability.
It will lead to small head scrathcing between DM and player. Which can lead to possible conflicting of views on what is suppose to be what...down the road.
In short, be concise, be constant, from the beginning, the middle, and end, to what is said about anything, especially when it comes to the overall view, on what can be done, by any said race.
We, this gerenation, are in the information age, so...it is as vitality important to make sure all factors are what they suppose to be, all connected supplements match the original message as well.
If not...this thread serves as an example, to what can occur.
Peace.
Elves were immune to sleep spells in 1st edition, and slept normally. It wasn't until the Complete Book of Elves (which was an abomination like few others) that the concept of trance entered the game, and only the Forgotten Realms setting embraced the concept.
I see no conflict with a race being immune to magical attempts to force them to sleep, and still being able to sleep by choice, just as 1st edition elves could be paralyzed, but were immune to ghoul paralysis. A specific exemption doesn't lead to a general rule.