Having worked as a Funeral Director I have been in quite a number of RC Churches. Some big, some small, some old, and some very new, some Congregations that were wealthy, some not. As in our Lutheran Churches, some were very ornate, while others are almost completely devoid of images, other than a simple cross or crucifix on the altar.
I have also been in some reformed protestant Churches which have lots of art; very "catholic" stained glass "iconic" depictions and frescoes. One in particular comes to mind, just a few blocks away from where I live; Knox Presbyterian in Stratford Ontario. It was built as a Presbyterian Church, and has the largest, and among the most beautyful Iconic stained glass in the city. They also have a side altar (which I find strange, since they are not sacramentalists.
I have also attended RC Mass which was held outdoors on a few occasions, where there was only a Cross.
In the plain, unadorned RC Churches, the faithful still gather joyfully to participate in the Word and Sacrament ministry of their Church. So, in a word; no, they are not needed.
Yes, if iconoclasts took away the images from my Church (as happened in the Peasants Revolt in Germany during Luther's life time), we would be as upset as he was.
Would it affect our Doctrine and Worship; NO!
God bless.