The act of fighting a bull through the use of damaging the opponent (The Bull) before or during the fight in terms of leaning the win much further towards the human is not justified.
It's a sport that dates back to the 1700s in Spain, And hundreds of years prior in other areas. While we can understand this tradition being popular in the past without too much judgement (ie the lack of knowledge or environment to practice moral decisions/opinions) its time should be over now, And looked back on as a lesson for the future.
Hopefully there's another avenue for the current Bullfighters/teachers/students/organisers that can replace their current field of work/passion, So as to set as little harm to all involved.
What spectators see is not a normal, Healthy bull, But a weakened, Half-blinded and mentally destroyed version, Whose chances of harming his tormentors is virtually nil. The bull has wet newspapers stuffed into his ears; vaseline is rubbed into his eyes to blur his vision; cotton is stuffed up his nostrils to cut off his respiration and a needle is stuck into his genitals. Also, A strong caustic solution is rubbed onto his legs which throws him off balance. This also keeps him from lying down on the ground. In addition to this, Drugs are administered to pep him up or slow him down, And strong laxatives are added to his feed to further incapacitate him. He is kept in a dark box for a couple of days before he faces the ring: the purpose of this is to disorientate him. When he is let out of the box, He runs desperately towards the light at the end of the tunnel. He thinks that at last his suffering is over and he is being set free — instead, He runs into the ring to face death.
Tradition is no excuse, We can't just say "we have been doing it for a long time, So its okay", Then slavery would be ok, And many other traditions which are now illegal in pain and other countries with bullfighting.
Neither can you justify by claiming: "I don't understand why people hate bullfighting so much, But don't complain about the animals killed at food factories". The animals in there are not tortured before their death, But rather killed in a way where they suffer little to no pain, Furthermore, This killing is done for the purpose of providing food for the citizens not for the mere joy of some tourists which find it fun.