But even ARM1 had some concessions to pragmatics, like push/pop many registers (with a pretty clever microcoded implementation!), shifted rigsters/rotated immediates as operands, and auto-incrementing/decrementing address registers for loads/stores.

Stephen Furber has extended discussion of the trade-offs involved in those decisions in his "VLSI RISC Architecture and Organization" (and also pretty much admits that having PC as a GPR is a bad idea: hardware is noticeably complicated for rather small gains on the software side).