It's interesting to read Von Neumann's perspective on CRT ("iconoscope") memory - saying how important it was not to lose the serial aspect of it since of course(!) you would not want to specify the address for every access, with most memory accesses being sequential (presumably meaning each bit of a 44-bit word), but it was advantageous to gain the speed of occasionally switching read location, which would be slower and more costly to do with delay lines (more, shorter, delay lines).

Note that Atanasoff's capacitor-based memory was based on rows of capacitors arranged around a mechanical rotating drum (a bit reminiscent of the later EDSAC's "initial orders" module!), so it wasn't true random access - there would be a rotational delay to get access to a given row. In a way it was as much a predecessor of rotating mass storage devices as it was of DRAM.

I just missed the core memory era myself, at least as a user, learning to program (while in highschool) on an IBM mainframe in the mid-late 70's, which was already using semiconductor memory. Still, years ago I bought a core memory module and a (very similar size) etched 6" silicon wafer, intending to frame them side-by-side as the defining story of my era - the switch from physical to solid state integrated electronics.