Why should I use the InkCanvas in WPF?

They really are meant to serve two different purposes. Canvas is for layout. Specifically for more exact control over layout using absolute positioning. InkCanvas is, as you know, for capturing and displaying strokes.

What you are doing is just fine, but InkCanvas has some nice additional features like EditMode among others. It is meant to save you from writing a lot of the stuff you would have to do by hand using Canvas. Using Canvas is a roll your own kind of approach where InkCanvas is a use a pre-built in kind of approach.

we can develop whiteboard application,paint application using InkCanvas WPF. EditMode gives us so many features like Gestures,drawing,,erasing,multi touch operations,select element drag drop options. insert elements like shapes,images,videos,stroke annotations we can save/load all strokes and elements. we can customise InkCanvas class.

An InkCanvas handles the mouse events for you to draw on the canvas. It also has this functionality:

• Save/Load
• Resize/Scale
• Highlight behind text
• Eraser mode

http://www.kirupa.com/blend_wpf/inkcanvas_pg1.htm

When performance in concerned, InkCanvas with real mouse events is much faster than creating a stroke out of StylusPointCollection, I found that adding new points to a StylusPointCollection is an expensive operation.