I am just curious as to why no one seems to address any reasoning for extended time the piston spends near the bottom of the bore when the intake valve is always more open and flowing near maximum mixture velocity.
Well it might be because that is simply not true.
Even with a massive change in rod ratio, there is virtually no change in piston position at BDC.
Neither is there any change in piston velocity at BDC.
There is almost no change in piston acceleration at TDC.
There can be a difference in piston acceleration at BDC covering a crank angle about 35 deg, + or - from BDC.
But while there is some change in acceleration, actual piston acceleration at or near BDC is only one half of what it is at TDC.
The bottom line again is...rod ratio simply does not matter very much.
A longer rod will produce a very slightly lower maximum piston speed at about 76 deg ATC.
A shorter rod will allow a lower block deck height, less engine weight, less vehicle weight, etc, etc.
The answer is that it doesn't change.Look at it from the point of view of how much the combustion chamber volume changes with longer or shorter rod in the top 10 or 20 degrees, + or - 5 or 10 deg. either side of TDC.