The discussion in #735 made it clear that on one hand the dev team is concerned about surprising users upgrading to a new version, and on the other hand a subset of users (myself included) desires the pre-0.15 behaviour of exactly enumerating which collectors should be enabled.

It seems like both sides could be addressed by having --enable.{collector} act additively, and using a different option to define the exact collector set. (E.g., --collectors X,Y,Z.) Arguably, users opting for the latter option are experienced enough where they understand they have to read the upgrade notes for any collector name changes.