Yes the new Photoshop Paint engine in CS5, does seem to lack some fairly basic features. One of which you have mentioned, that it would be nice if pressure sensitivity could be more closely defined (to do more things), like you say.
A more general point. What they seem to have tried to do in CS5 is to integrate the new painting features, directly into the old painting features. This in my opinion is not the smartest decision. The whole "painterly" thing needs to be better implemented, more intuitive and visually oriented. Its lacking in features. Using ARTISTS to come up with ideas on how this should be done. A proper series of painting "Palettes", for brush selection and color mixing etc. Those kind of things.
I think referring to Thomas and John Knolls initial ground-breaking work on the application istelf, is the way Photoshop SHOULD be developed. Not by … software engineers alone. Its a huge mistake to go down this route, and I see it more and more in new Photoshop features.
To be more specific - its not particularly intuitively implemented if you ask me at the moment: Very difficult to get an idea from the brush preview what's supposed to be happening with the brush tip. Very difficult to define the actual meaning of the brush parameters. Too many sliders. And nib rotation, which to be fair I hear they are working on with Wacom at the moment.
This is all great. I hope the brush icons indicate the direction of rotation in future updates. This can't be that hard to implement, at least based on my complete lack of programing knowledge! ;^) It seems like it could be a minor revision push out. Currently Wacom user's must maintain a constant awareness of the location (rotation) of their Artbrush Stylus's rocker switch in order to know the orientation of the brush. Brush icons need to rotate visually so that it is more intuitive.
. This can't be that hard to implement, at least based on my complete lack of programing knowledge!
Yes - but the achievement would be to break through these technical considerations, and flexibility, into a truly easy to use and understand interface. This was the great achievement of so much the early development of the application.
Photoshops new 3D features and Brush Engine are both examples of truly great, rich and powerful new features with really poorly designed interfaces. These have not been designed with any visual intuition, or visual logic. These features are really so poorly designed in their interfaces - that they are likely to be ignored or abandoned by most users. A lot more effort and left brain thinking needed on interface design.