From a practical perspective, many more bugs than are
being marked as
"normal" are actually "normal" by this standard. Most of the bugs
in
our database are probably "low" priority in the sense that we just
can't get around to fixing all of them. I can see the argument for
making the most common case the default (though I share others
uneasiness with doing so).
A good thing is that if the default is normal and the bugmeister then
lowers it, that gives a negative feedback to the reporter, whereas if
it's as the default, it doesn't.
Most bugs that are bugs should be normal, but perhaps we don't have the
resources to fix each of them.