1/ mdl_log is a huge table in existing installs - it would be technically very hard to tweak it, it would not be possible to migrate old data to new structure - I believe that the only way forward is to rely on new database table(s) in plugins
2/ The "new framework" fixes original events and logging at the same time - both of them now receive more and better data.
3/ The new events and logging includes full backwards compatibility, this would not be possible if we just altered events and logging.
Anyway the new events are already part of Moodle 2.6, I am afraid there is no way back. I expected developers would discuss the actual PHP interfaces now.
Future major features
Request for comments - new logging API
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