...I think you highly underestimate the value of stasis. Of the ability to instantly say "fuck you" to any incoming damage.
It's a must-buy on some champions, and amazing on most mages. It's not "only good on champions who have short cool downs", it's good on anyone who's relatively immobile and vulnerable to being jumped on (hence why most marksmen would love to have it as an AD item).
You don't play mages much do you? The only thing most people even buy it for is the armor.
I've been primarily top and bot recently, but, yes. I do play mages frequently. And it's great on quite a lot of them. Just not many of the ones I play (Ahri, Karthus, Morgana), given that they either have the durability to render the active relatively pointless, or the active would harm them more often than it helps.
The active is situational at best, and more often than not just puts you in a bad position.
Situational? Somewhat. Does it put you in a bad position? It can if you misread your team, or misuse it. But generally it won't put you in a worse position than you were in before - it just leaves you in the same shitty position.