It would amazing if I could encrypt everything new or modified files in Drive just by using InSync.
I really wouldn’t want that.
Insync development is slow enough already, but still you see various issues in basic syncing.
Diverting their resources to develop a new and difficult feature such as encryption would only further slow down their development. And considering how error prone encryption is, I wouldn’t trust it to Insync.
I’m happy leaving client side encryption to another dedicated tool.