Why was Davies–Meyer chosen over Miyaguchi–Preneel most of the time?
Some ideas (not a definitive answer):


Davies–Meyer is one of the two simplest among the 12 secure methods by which a block cipher and XOR can be turned into an iterative hash with one encryption per block, per the analysis of Bart Preneel, René Govaerts, Joos Vandewalle's Hash functions based on block ciphers: a synthetic approach, in proceedings of Crypto 1993.Note: in the above table, the block cipher $E$ uses its first argument as key.
Davies–Meyer (method 5) is the only of the 12 that works with a block cipher having a key of width different of its block without needing an adapter (the g in the first drawing of the question).
When the key is wider than the block, that characteristic 2 makes Davies–Meyer use less encryptions for large messages, and that can translate into a speed advantage.
MD4, which was influential on MD5, then SHA, SHA-1 and SHA-2, essentially used Davies–Meyer (except for replacement of XOR with modular addition on a word).