There are two parts to this request, sort of connected:
1) Editing volume of an audio event should use envelopes ON the actual event. Just like the fade in/out sliders exist on the event itself and there's no need to expand any automation views or tracks. And just like the volume handle of the individual clip exists ON the event itself, you should be able to double-click along the volume line to add an adjustable envelope.
2) The volume adjustments should be instantly visible on the waveform. Just like when you fade in/out, or raise/lower the volume handle, there is visual feedback of the fade or volume change - so too, there should be visual feedback in the waveform of the volume changes along the clip by the envelopes.
Tip: if there's an issue of raising envelopes higher than the boundaries of the event, as they will enter the ground of the track above, the simple solution would be that the envelope "dots" and "lines" that are higher than the clips boundary only become visible when the event is selected. (Wavelab's solution is to limit you from raising the envelope higher than the clip's boundaries, but sometimes I need it louder!)
Here's a snapshot of WaveLab (which has this feature):