In the process of restoration, especially when readability is the key standard, outlines, edges, contours, which help define the imagery, are reinforced. Even if the original is relatively readable, it can be made more readable. And in areas where the original surface has been lost over the centuries, the restorer repaints them without compunction, in the name of readability. All this happened at the Sistine Chapel where Michelangelo's ceiling frescoes are today definitely more readable than they were before 1980. To be sure critics and artists have found that the imagery appears to be too much like highly readable Walt Disney illustrations.
Tastes change, as art styles do, and sometimes very fast.
Thus the time and taste behind the treatment is left indelibly on the unique text. The art object needs to be made assessable to the lowest common denominator. The notion is similar to the one behind Classic Comics, where Dante's Inferno or the Holy Bible is cartoon-ized for school children. The tourist industry is one of the leading business of the grandest cities in Europe and America and in places like Paris, New York and Rome, it represents the single greatest income producer for the local economy. In order to make the art palpable to mass tourism, the assumption is that the art objects should be readable, so that the visitors are satisfied in their rushed visits to the Louvre, the Met, the Uffizi.