The 2.54mm (0.100") pitch sets the board footprint — standard for this class, so routing traces between rows is straightforward on a two-layer board.
Tin contacts — mating cycle reality check
Tin is the workhorse finish for moderate-cycle applications — typically 25 to 50 mating cycles before the plating wears and contact resistance drifts. In a production harness that gets mated once and then lives in the vehicle, that's fine.
The blue insulation color is a visual key on the assembly line; it matches the Micro Quadlok series coding.