To be fair, that line drawn by China was her biggest diplomatic mistake. It created so much mistrusts toward her among ASEAN nations. Any iterations of peaceful rises and securities on commercial sea lanes become hollow. Her insistence on bilateral negotiations are taken as bullying.
Her real intentions, as far as I can understand, are since those rocks do not belong to any one nation, China being a neighborhood country too has every right to share them. But her ultimate concern is she doesn't want any one nation to have hegemony over those islands because that's where her increasingly large fleet of merchant ships must go through.
China is not using her big power policies well yet, but in time she will learn.
Hard to say.
USA has Guan hundred times farther away from USA main land, nobody questions it. Thus, distance is NOT an issue. How about the conflict over Falkland islands between UK and Argentina?
Guan claim is based on WWII legacy, by force. Chinese claim of SCS is based on historical heritage activities, not by force.
Admit it: current international norms are built on Western regulations more or less enforced by forces and threat to use forces, which are in turn based on use of forces. Thus, China’s claim is doubted by many, especially those once thoroughly conquered in the past by West.
BTW, China's control of SCS doesn't mean the sea lanes are not open to public transportation. Thus, your statement "Any iterations of peaceful rises and securities on commercial sea lanes become hollow." is a twist of truth, if it is not an outright lie.