If the KIM-1 has a hex keyboard that allows you enter machine code, is there even any ROM. There would seem no need. Nothing to store, everything is interpreted directly in machine hex

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JMP $FFD2

Yes, there is a ROM. The KIM stands for Keyboard Input Monitor or some such thing. The ROM manages the keypad and also manages working off of the "serial" (it's not RS-232 on a stock KIM) teletype.

It's actually a quite a bit of circuitry to make a standalone keypad and display compared to some switches, LEDs, and a CPU with an I/O chip (the 6530 in this case). The actual discrete logic to handle that is not particularly trivial. I would say that the circuitry for a computer is simpler than one for a keypad/display.

Without any code to run when the processor comes out of reset, it won't know how to do anything. That initial code normally needs to be in ROM. Without that code, it wouldn't know how to scan and debounce the keypad, or interpret or put your punched-in machine code in RAM, or feed the display, or run a serial port, or anything else.

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http://WilsonMinesCo.com/ lots of 6502 resources
The "second front page" is http://wilsonminesco.com/links.html .
What's an additional VIA among friends, anyhow?