Grace & Peace!
Kalt, I’m going to take a stab at a response, but keep in mind I’m no art historian!
A lot of the modern Christian artists seem to be very evangelical protestant, and to me their aesthetic leaves something to be desired as it often borders on kitsch (again, to me).
I think the difficulty with modern Christian art is that it does not tend to be devotional in nature–it is either purely didactic, or purely emotional (sometimes merely sentimental), and often what amounts to these dual requirements of didacticism and sentimentality have the combined effect of strangling the art out of a piece of religions “art”. Popular pictures of the smiling, friendly Jesus are a case in point, for me. As such, I tend to prefer medieval and renaissance Catholic art, as the more we get into the Baroque, the more sentimental and soppy things seem to become. Romanticism in art generally had the effect of a re-appraisal of things medieval (witness the rise of the neo-gothic aesthetic), a re-appraisal for which I’m grateful.
(Just as a side note on contemporary art and religion, there was an interesting article in Art in America or Art Forum or something like it some years back which was basically comparing the art of Protestant and Catholic artists. For the most part, they found that Protestant artists, or artists who were raised Protestant, were more abstract, whereas a number of the artists characterized as abject (utilizing body fluids, hair, etc–think Andres Serrano) had more Catholic backgrounds. The suggestion the article made was that Catholic art tended to focus on or at the very least acknowledge the fact of the human body in space, whereas Protestant art eschewed the body and tended towards intellectualism and abstraction. Could it be that the latter aesthetic stems from a reliance on the authority of text/scripture and the former on the acknowledgment of the importance of an embodied tradition?)
I think the gloominess that you identify in the paintings, though, can possibly be chalked up to a couple things:
1–The belief that art should inspire in its viewer the same attitude that God has toward his creation. A piece of art which aroused desire for what was depicted was considered obscene or pornographic. A piece of art which repulsed you was considered disgusting. But a piece of art which created and maintained the distance between creator and creation–that was truly art!
2–An attempt to depict the serenity of divine apatheia. Cleansed of all worldly attachments, desires and impulses, the serenity of the saints could easily look to us like gloominess!
3–The idea in the late middle ages / renaissance that the man of learning (also the man of holiness and religion) was dominated by a melancholic humor (as opposed to phlegmatic or choleric) and/or was born under or otherwise influenced by Saturn, the planet of melancholy, depression, sadness in its malefic aspect, but also of learning, meditation, contemplation in its beneficent aspect. A saint or scene depicted as melancholic could have been an artist’s attempt at showing aspects of wisdom or contemplation, or of inspiring such things in his viewer.
4–Also in the late middle ages, northern European piety seemed to focus very much on the pain and physical horror of the crucifixion, resulting in such masterpieces as Grunewald’s Isenheim altarpiece in which Christ’s body is covered in ghastly sores, pierced by twigs, and has the coloring of a corpse a few days old. The piety which fostered devotion to the five wounds comes from a similar place.
5–The idea of the sublime and the beautiful. Granted, this was not a distinction made by ancient artists–Edmund Burke (I think) was the first to posit a formal distinction between the two–but I think this distinction is useful when sacred art is under consideration. In sum, the sublime is an experience of beauty in which that beauty is a source of fear, terror, or danger. It is an intuition of the boundlessness of the infinite and a realization of the smallness of one’s own being. For the most part, I think religious art tends toward wanting to create an experience of the sublime (think holy fear). Sometimes that experience is awe-inspiring, but not necessarily pleasant.
Regarding the difference between the paintings and the books, I think that patronage played its part in both media, but not necessarily to gloomy or sunny effect. A book is far more practical for devotional purposes than a painting (if only by virtue of its portability), and often admits far more opportunity to explore more decorative arts (such as in the margins). A book may also be more private and therefore not subject to the aesthetic requirements to which a public work of devotional art could be subject. In terms of Books of Hours, they were quite expensive and affordable to only a few. The visual pleasure of seeing all of that decorative art could have been one of the things justifying the expense.
This is just my conjecture–perhaps someone here better qualified will chime in. I hope so!
Under the Mercy,
All is grace and mercy! Deo Gratias!