The Perfect Tense versus the Preterite

It appears that in certain western European languages the Preterite
tense has lost ground to the Perfect tense, at least in the spoken if
not the written language.
A perfect example is French which only retains the Preterite in the
written form, although the Preterite was formerly used in speech. I
believe the same process is also happening in German and may have begun
in *European* Spanish as well; although *Latin-American* Spanish still
retains its traditional tense usage which largely corresponds to the
English usage of these tenses.
Can anyone offer any insight as to why the Perfect tense is now being
used in situations where the Preterite would have used formerly? Also
is this process found in any other languages, and is it a manifestation
of the mysterious Sprachbund phenomenon?
Incidentally, from my admitedly anglo-centric viewpoint, I would have
expected the trend to have been in the opposite direction, as the
Preterite would appear to be a more economical and concise method of
expressing the past.
I look forward to your replies, and corrections.
David.