It's quite simple -- I do not consider my job as being one of automatically pushing any patch that reaches the passed-QA status.  I will take the time I need to review and test nearly [1] every patch, and in particular any like bug 7167 that proposes a significant change.  Bigger patches take more time, especially those that have architectural implications.  The revamp of the schema update mechanism proposed in bug 7167 has been under discussion for a long time, and is not IMO one that should be automatically pushed, especially given that it's been quite a while since patches have been rejected simply because of merge conflicts with updatedatabase.pl.

Further, I *do* view my job to include responsibility for final review of architectural changes to Koha.  A patch that adds a necessary improvement to Koha but whose implementation is lacking or would present long-term maintenance issues is going to receive enhanced scrutiny from me.

There are other major architectural patches, most recently and most notably DBIx::Class support, that I have been focusing my effort on; bug 7167 in my estimation is not at the same level of priority.