The author of an answer on math.se remarked that much of mathematical progress is a factor of the accrual of both, theorems, which other mathematicians can use in their proofs, and more efficient proofs of those theorems, which enables, students, and mathematicians, to apprehend them faster than they would have otherwise apprehended them.
In the paper A Beginner's Guide to Forcing, Timothy Chow introduces the phrase open exposition problem, which he uses to denote all theorems for which there is no proof such that any person capable of apprehending the premises would, after s/he read the proof, disbelieve that s/he could have inferred the conclusions him/herself.
Considering that, it seems to me that mathematicians appreciate how succinct expositions affect the progress of their discipline.
I study undergraduate math and philosophy. Next year, I'd like to submit an essay on the importance of solving open exposition problems in philosophy to an undergraduate journal. Before writing it, I'd like to read what mathematicians have written on either, the effect of the simplification of proofs on the progress of mathematics, or how to simplify proofs. Have mathematicians written on either topic? If so, could you recommend some titles.