WIthout a stylus, a feature which allows to (pinch-) zoom into sketches would be helpful to fit more meaningful content than what is possible by drawing on the screen with your finger.
Skecth feature is really marginal into Omni Notes: specific apps are great for draw, their artifacts can then be shared with ON for categorization and context addition with text or whatever.
WIthout a stylus, a feature which allows to (pinch-) zoom into sketches would be helpful to fit more meaningful content than what is possible by drawing on the screen with your finger.