Many people try to make a false distinction between modern and traditional Catholics. Most of the time however, what they are really talking about is obedient vs. disobedient Catholics. A person can either be modern or have an inclination toward traditional ways of doing things, but no one can legitamitely call themselves Catholic if they go against Church teaching and violate her precepts.
Let's take two people and compare them. One is a man named Jim. He goes to Mass on Sunday, tries his best in most things, but doesn't do much church-related stuff outside of this. He likes Masses which feature guitars and saxophones, and church builidngs which are modern-looking. Outside of church, he likes to spend time helping out at soup kitchens, or volunteering at the animal shelter.
Another person, a lady named Joanne, goes to daily Mass, goes to confession every week, prayers the rosary daily and says many other prayers. Often in her spare time, she will read the Bible or the Catechism. She enjoys Masses celebrated with great reverence along with incense, bells, and solemnity. She enjoys going to Latin Mass whenever she can.
Based on the information above, both of these individuals are good Catholics in good standing with the Church. One is not "better" than the other. They both have preferences as to specifics, but in essence, they are practicing Catholics. You could say one is modern, and one is traditional. But neither is disobedient.
Most of the time, when you hear someone speaking about how the church has to modernize, what they are really saying is that the church has to drop divinely revealed truths and substitute them for that person's own preferences. The Church was founded by Jesus Christ, who said he is the Way, the Truth, and the Life. Jesus also established a Church. It's not as if Jesus lived and everything was recorded in the Bible, and any way we decide to live is ok because it's all man-made and Jesus is just an example for us. The fact is, Jesus specifically established a church, and gave her power to bind and loose, to make decisions authoritatively. Jesus gave us a shepherd, the first of whom was Peter to guide us into all truth.
You cannot simply accept Jesus as a non-committal buddy who makes you feel good about anything you decide to do. Either Jesus is the Son of God and our Lord and Savoir, or he is a liar who deserves no allegiance from us. You cannot make Jesus into your own image. The Church has been given the power by Christ to make binding decisions.
You may not like some Church teachings, but it is our obligation to try to understand them and live by them. It is ok to struggle with a teaching, but it is not ok to set ourselves up against God. Also, just because you
want to believe something, doesn't make it true.
I hear so many people saying they want to change the church. I heard a young lady one time say she does not want to change the church, she wants the Church to change her. I struggle to be a good person, just like everyone does. But I do not think it is useful to simply dismiss anything which seems difficult in order to avoid struggle.
People who claim the church needs to modernize simply want the Church to change her teachings to suit them. Without ever investigating why the Church does what she does, they feel they have the right to dictate to the Church how she should operate. They demand Church acceptance of abortion in some cases, contraception, women priests, gay marriage, etc.
Christ constantly talked about division of people. He did not say everyone was right, in fact, he said quite the opposite. He said there would be good seed and bad. That there would be thorns as well as flowers. He said he came not to bring peace, but a sword and that there will be divisions even within families because some will proclaim the truth, while others won't. He said Christians will be persecuted for their faith. Jesus never said everyone is right and you just have to get along. Jesus came to show us the Truth, no matter how hard that may be for some people to accept.