Sleep:
A sleep spell causes a magical slumber to come upon 4 Hit Dice of creatures. Creatures with the fewest HD are affected first. Among creatures with equal HD, those who are closest to the spell’s point of origin are affected first. Hit Dice that are not sufficient to affect a creature are wasted.
Sleeping creatures are helpless. Slapping or wounding awakens an affected creature, but normal noise does not. Awakening a creature is a standard action (an application of the aid another action).
Sleep does not target unconscious creatures, constructs, or undead creatures.
Vs
You exert your will against your foes, seeking to overwhelm them
with a tide of magical weariness.
[Sleep keyword]
Target: Each creature in burst
Attack: Intelligence vs. Will
Hit: The target is slowed (save ends). If the target fails its first saving throw against this power, the target becomes unconscious (save ends).
I just don't feel this amazing contrast.
The 3E version tells me about HD affected and wasted HD. The 4e version tells met that I attack all targets in the AoE.
The 3E version tells me that it's a magical slumber which can be broken by slapping or wounding (as a standard action - doesn't get more immersive than that!) but not noise, and that it doesn't affect the unconscious or the unliving.
The 4e version tells me that it's a sleep effect (via the keyword) that slows the target and might render them unconscious. Some other things - like the effect or non-effect on unliving targets, and the possibility of waking someone as a standard action - are shunted to other parts of the rulebook (MM glossary, and PHB Heal skill rules, respectively).
I don't feel any contrast. The Rolemaster sleep spell is even more spartan in its description than 4e, but Rolemaster is nevertheless (in my experience) a very immersive game, because of the intricacy of the interaction between ficiton and mechanics.
In each case, reading the sleep spell isn't about being immersed by reading. It's about envisaging about how an episode might play out in the game.
That's why I believe it is a matter of discourse and not simply language. The immersiveness of Rolemaster, I would argue, is a product of the correspondence between the discourse of the game and the orientation of the player - which of course, like so many things in RPGs, is subjective.