VST2 SDK is no longer in active development or support https://www.steinberg.net/en/newsandevents/news/newsdetail/article/vst-2-coming-to-an-end-4727.html
The use of frameworks should make things easier for devs and is just indicative of a modern SDK.
Amazing that the likes of NI aren’t fully on it yet though, but it’s not all that surprising when their main container plugin (Komplete Kontrol) you can’t even resize. I think MIDI 2.0 will genuinely play a part in the increased use of VST3 however.