This is nothing to do with actual tranquility (in the sense of passaddhi), which is basically the opposite of everything you are describing.
You don't cultivate tranquility by not knowing "not caring" about worldly factors; you cultivate tranquililty by abandoning the five hindrances (covetousness, ill-will, sloth, agitation, and compulsive questioning).
The Upanisa Sutta says that tranquillity comes from rapture and leads to happiness (the Samaññaphala Sutta repeats this). The precondition for tranquility is rapture, not "not caring about the state of the world".
Tranquility is a mind that maintains a spacious calm in the face of adverse conditions. It's nothing like what you're saying.
Your view is harmful because you're saying that someone without tranquility (with covetousness, ill-will, sloth, agitation, and compulsive questioning, without rapture), will be better equipped to deal with worldly problems, but the exact opposite is true: tranquility creates the space to deal with worldly problems more effectively. It's harmful to advocate for hindrances because you claim that means people "care" more.
Right, but it can and should be maintained while dealing with tumultuous events.