I personally prefer using the php format over the JSON, due to
multiple encoding issues I've hit in the past and not having to deal
with the small intricacies (and potential problems) of the JSON
encoding/decoding on each end (the main that comes to mind is the
issues of associate array key names in the JSON->PHP)
For me since I'm writing my MW interaction/bot/script/etc code in php,
its VERY nice to easily get a native php array of info via format=php
and unserialize(). On that same note, the pretty html print mate to
php (txtfm) is invaluable for debugging/viewing the format of the
return structure using a webbrowser and the GET url format.
If i were writing in another language, be it application,or live JS, I
would indeed seen the prevalence of JSON and/or XML, but if I'm
botting from php, accessing MW in php, why not keep the info in a an
encoded array format that is more native from end to end
Just my 3 cents.
That being said, I agree and support the idea of cleaning up some of
those more ancient formats if they are not being used.
Would there be anyway to hack in some temp tracking code to
record/track the usage of each format for the top popular WMF sites
(thinking EN:WP and commons are the first 2 coming to mind) to show if
any of them are being used at all, and to what extent?