Go look at the power I mentioned. It's an Interrupt, it's better than another At-Will, and it's not alone.
It's not as good as well.
First: It's ranged. So it will provoke from creatures next to you when you use it. Better hope you aren't on the front lines like a defender and often surr- WHOOPS. Guess you better hope no enemies are nearby to thump you into the dirt when you use it. WLMR I'd like to point out has no such disadvantage given you're using a melee or burst attack to begin with.
Second it only applies to melee attacks. The attack from WLMR will be against
any attack that targets you. No getting around your attack using bursts and blasts (or just attacks that won't trigger it). You get that attack no matter what he does!
Third, it can be easily and trivially avoided simply by attacking the swordmage. It's not a catch 22 and no way guarantees you an attack. WLMR and a mark is a catch 22, you WILL get your immediate action attack one way or the other - or the creature does nothing.
It is also a level 3 power, while WLMR is going to be in paragon tier. But if you think that is as good as WLMR then you've got to be kidding.
You are basing your argument on a false dichotomy.
It's not a false dichotomy.
The way it worked is exactly as I described: Either they attacked you and were attacked. Or they attacked an ally, took a -2 penalty and were attacked. That is the inherent power.
The encounter you bought up isn't a catch 22. It can be circumvented immensely easily by any monster that is vaguely intelligent. It works once per encounter, while WLMR will work
the entire encounter all of the encounter while you have an immediate action. In addition, nothing stops you from taking powers like that and putting a marked target under a catch 22, plus using something else if it dies or similar.
I can have my cake and eat it as well. While you just get the left-over icing. This is why it was nerfed.