I'm looking for information whether there has ever been an official statement by Commodore back in the days on why the Original Chipset was limited to doing 6 bitplanes only when running in low horizontal resolution.
Enabling 8 bitplanes in low resolution would have saturated the chip ram bandwidth, much like 4 bitplanes in high resolution, therefore making the machine sluggish as 4 bitplanes high res makes it. But then, why not limit high res to 3 bitplanes?
Adding 2 more bitplane pointers, 2 more shift registers to Denise, and more CLUT registers does not seem to me like a huge hurdle, even in 1984/85.
What other reason could it be?