This article fails to mention Spain's Civil War, when fascist Franco's forces, with help from Hitler and Mussolini, went against both Catalans and Basques (look up the bombing of Guernica). That left wounds, so not just university students but also the older people who suffered through it, all want a vote to be held.
After all, if a recognizably different group of people who want independence need to ask permission from a central government that doesn't want them to go, how can they ever become independent?