Deprecate private variables and methods?
Shall we deprecate private variables and methods? They seem evil, since they make it more cumbersome to extend classes.
We're actually trying to use them in new code because they help in separating abstractions and give us better better control over proper interfaces to access data. You can't force people to uses accessor methods if they still can access class variables directly. Unfortunately, due to PHP's low entry requirements, many PHP programmers know nothing about proper OOP/OOD and produce such opuses instead.
Protected seems preferable, for extensibility purposes.