Arguably the two most important features of RISC, for the modern era, were having regular instruction sizes leading to easier parallel decode and having at most

Arguably the two most important features of RISC, for the modern era, were having regular instruction sizes leading to easier parallel decode and having at most one memory access per instruction making the combination of pipelining and precise exceptions much less of a pile of worms. ARM's 32 bit ISA was very regular and it mostly had a single memory access per instruction, but there were some like store multiple which could potentially save every register to memory. By getting rid of that in A64 and replacing it with an instruction to concatenated two registers and stored them in a single memory access they ended up in a far RISCier place than A32.