"Why do we pray? To request that God retrospectively re-arrange the
universe back at creation, so that what we have asked for now will
happen inevitably? Or do we pray that God will intervene directly in
the warp and woof of the here and now, to achieve something genuinely
new?"
None of the above! I pray because I believe a loving God answers prayer,
and he tells us to. I leave the details of how he does this to him. The
mechanism has nothing to do with the "why". Frankly, I believe he could
use either of the methods you have described - and others we are not
likely to come up with.
Gordie