The presets made sense in < 4.0 versions because the Y axis of the graph was based on relative values, ie the bottom of the graph was the previous key value and the top of the graph the next key value.
4.0 works differently. Seeing the entire curve is so much better and it is very easy to get the curve you want, without needing to store handle positions as a preset. We do still provide some preset buttons for ease out, ease in, bounce, flat. There is also an auto Bezier mode that adjusts the handles based on the surrounding keys.
I posted a bit more on this topic here:
Curve Presets in 4.0
