Good point.  But I think your questions are based on too narrow of an assumption: that liberal or conservative bishops do not have a common wish for decentralization, as long as the conservatives are not blindly wed to the traditional as if it is unchanging.  We have had in the US, for example, many "conservative" bishops who have been quite open to reforms, albeit more guarded then not.  It was vey conservative bishops who allowed changes in the liturgy in their dioceses and immediately began saying Mass in English.  What we have - in both politics as well as the Church - is not really conservatism, but is clearly reactionary regression and the clinging to a set of traditions that were rather radical changes in their time.  Most everyone can accept a "conservative" or a "liberal" bishop, as long as change is done with plenty of education and discussion, and a sincerity in hearing what others say.  Our current challenges are not, and never have been, as black or white as you pose them.