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"make it easier to code right"
Didn't matter.
High performance, minimal memory use was essential.
Easy to code was irrelevant.
Remember, early games had microscopic amounts of memory on very, very slow processors with no actual devices. Stuff was connected -- essentially -- directly to the CPU chip.
I would assume there were a much larger percentage of programmers that both knew assembler and wouldn't think twice about programming in assembler. And even into the IBM-PC and AT days folks that never really programmed anything but assembler were still around and could easily program circles around the C and Pascal programmers.
Pascal, and C were wonderful (for desktop computers) once they got a foothold and you could afford a compiler, you were happy to just be programming in some new language and had never heard of an optimizer, you just assumed the high level language turned into the machine code the same way with every compiler. You still easily fit your programs on a 5.25" floppy. And had plenty of that 640K to spare.
I think we need to bring back or have more 4K programming contests. Write a game for the GBA or NDS but the binary, data, code, everything, cannot be larger than 4K. Or perhaps re-invent the gameplay of asteroids, rocks, ship, bad guys, missles, don't worry about the video pixels because, first it wasn't, and second that was handled by a second processor (well hardware state machine), just generate the vector drawing commands. There are free 6502 C compilers out there now, and p-code based pascal compilers that it would be easy to run the output on the 6502, and see if you can get the frame rate up to real time at 1.5mhz or whatever it was running. And fit in the prom. I think the exercise will answer your question. OR...just make a runtime p-code interpreter and see if that fits. (standardpascal.org, look for the p5 compiler).
A handful of Kbytes is like a thousand lines of code or less. There just wasn't that much to the program, and assembler isn't difficult at all, certainly not on a 6502 or other similar systems. You didn't have caches and mmus and virtualization and multi core, at least not the headaches we have today. You had the freedom to chose whatever resister you wanted, each subroutine could use