One possible connection I see between all the evidence theyve asked for is this
Reasonable doubt. A large part of the DTs case on through closing arguments was that LEs investigation and testimony couldnt be trusted. Jury cant do anything with that, except to ask- is it possible that any key evidence was tainted by LE bias?
Which evidence? The dolls measurements. What LE said they saw and heard during their interview with Ross. Finding Leanna suspicious ( and by inference, Ross suspicious), without foundation. Whether or not LE accurately described what RH did at lunchtime with the lightbulbs.
To see for themselves, to remove any filter of LE bias from the evidence. To take LE bias off the table.