With basic math.. this is the most RIDICULOUS suggestion ever. SC has uses already. I for one, use it in pretty much every pull in WP speed runs. Clever use of cooldowns makes useful you just need to find the situation, like many other abilities.
Let's play with your idea a little bit. (P.S. I'm going to play around with averaged numbers based on a relic and darklight+ geared warrior)
Let's just imply that it gets the 150% heal. We'll use 4 targets for this point.
The average hit of a steel cyclone with just berserk active is ~350-400. For the sake of ease let's use 400.
400x4 = 1600
1.5(1600)=2400. Using 1 Steel Cyclone on a group of mobs that isn't even threatening is giving yourself a free Cure II crit from an equally geared White Mage. Redundant.
Lets use 7 mobs (the pull in WP between the room after the first boss and the next door).
400x7=2800
1.5(2800)=4200.
This is a little less redundant because you'll already be taking a lot of damage in this pull.. but when you can throw 2 of at any point in the fight for emergency heals.. either you're overhealing and wasting wrath or just making the whm overheal. OR you were already almost dead and used it properly (thumbs up). How about we add another cooldown into the mix. Internal Release. 30% for 15s. Let's say 1/3 of the hits crit (rounded down). You now have 5 hits and 2 crits. It'll look like this:
1.5(400x5)(600x2)=4800
A free 600 more healing for popping 1 short CD outside of the GCD.. quite strong. But now lets add 1 more cooldown.. for more overkill on how much this skill could heal. Bloodbath. 25% MORE raw healing on those hits.
0.25(400x5)(600x2)=800.
4800+800=5600.
That's over half of any warrior HP pool (and most of them could even have Thrill for Battle popped and still have that statement be true). in 1 GCD...And with infuriate you can throw another on the very next GCD. This isn't even putting in the extra damage you want the ability to do. Needless to say it doesn't need near as much love as you're suggesting. I personally think it's already relatively useful as is. Using it with Bloodbath during an AoE pull provides a lot of self healing and still pours some solid damage over the group (and has the built in defiance modifier of 2x enmity plus the healing agro). It's certainly not something to be spammed about, but with proper timing its still rather useful.
P.S. The idea of an AoE ability isn't to be as effective as the strongest single target ability when only 1 more mob is added. The golden number I've seen other games use for equal effectiveness is between 3-5. A fair suggestion for giving it a healing effect would be say.. 75% damage as healing? That way it's equal to IB on 4 mobs, and more efficient on 5 and greater without changing the damage modifier as we're "not here for high potency attacks"
P.P.S. Usage of Wrath attacks outside of being able to Infuriate the Wrath back immediately is generally not a great idea as is. So to use Steel Cyclone/Inner Beast at any point, you should be ready to Infuriate so you -don't- lose the Wrath benefit. The exceptions are of course emergency self-heals or the cases where healing is not needed and you want to pump out more damage.