There are many reasons a card would default to a higher level, but in
the end it is basically tuning the card for a server application.
A warning that some cards default to high PCI latency values; settings that can interfere with latency sensitive devices such as sounds cards - this could be a help to others.
A warning that there are quite a few cards that subtly corrupt your data
if you don't have the latency set to values to work around chip errata is
also worth making.
You fiddle with PCI latency values at your peril, and preferably with the
data sheet and errata docs to hand.
Alan