The Catholic Church has done some "splintering" of its own, or should I call it "schism-ing"? It's true that there are way too many Protestant denominations, but I believe that this will change.
Protestant churches agree on the essentials of biblical doctrine, but some Catholic dogma clearly departs from biblical doctrine. Protestants are taught to look to the Bible and the Holy Spirit as our source of guidance as to how we should live as Christians. Believe it or not, when we're in the Spirit, there is unity! Catholics are taught to look to the Bible (possibly), other "sacred" writings, and a mere man who claims infallibility, which is their source of unity. I apologize if this offends anyone, but I don't believe there are any infallible men except one--Jesus Christ!
I grew up in a predominately Catholic city. Some of my closest friends were Catholic. One thing I noticed is that the Catholics I knew tended to look at Catholicism as just a religion--something to be observed at church, but not necessarily something to live out 24/7/365. Also, their religion was important to them, but they didn't seem to have a personal relationship with Jesus Christ. Of course, Protestant churches are filled with those who don't have this relationship either, but I've known many Protestants who do.
This probably sounds cliche, but that relationship is what matters most to me. I literally could not live and breathe without Jesus! He is everything to me. He is my life! I believe that He wants everyone to know His love and to know HIM in a very personal way.