I like the idea of having "per-directory" plugins. It could probably evolve to "start JMeter without plugins" or "enable-disable plugin from a menu".
What makes me a bit sad, PR 181 does not provide tests (it does not test that new folder works as expected). I have no strong opinion regarding inclusion of the feature to 3.0 vs 3.1 . I have no idea how much resources it takes to release JMeter. If possible, it could make sense to release more often, so we do not have to vote on "delay current release vs move a feature to the next one". The feature looks not that intrusive (provided it is tested), and it looks to be of a great use, so +0...+1 for inclusion the feature into 3.0. Vladimir