Besides the fact that VST3 is out for a long time already and offering several improvements (Sidechain, Idle off etc.) there was a point in regards to MIDI which is really a downside.
I can’t find the post atm but I am certain that even Matthias oder someone from Steinberg wasn’t aware of the lack of a specific MIDI functionality with VST3 and they wanted to take it to theri devs. MIDI 2.0 may be a game changer and perhaps this specific MIDI issue will then be no longer a problem?
And, hey, since VST3 isn’t new anymore, is VST4 somewhere near to come?
Here is the topic I was mentioning:
VST3 and MIDI CC pitfall - Developer / VST 3 SDK - Steinberg Forums