As for bryce's UI, we do have to realize that part of its simplicity is due to its visual style, with clear icons and relatively uncluttered state.
There's also the psychological impact. Bryce's interface looks friendly and far less intimidating then a technical interface as found in many other applications. However, this does also prove a problem when integrating increasingly much functionality in it.
Bryce's interface style requires a lot of space for relatively few settings. I mean, take your average skylab screen. The sliders displayed in there on one entire screen could easily have fitted in just the left col of that same screen if a more technical interface style had been used.
This means that adding more tools will inevitably lead to the need for increasingly more 'labs' which will eventually start to impact workflow. Or the interface will have to change appearence rather significantly to facilitate a much more compact visual style.
Sticking to the current UI will limit the amount of functionality insertable into bryce.

(_/)
(='.'=)
(")(")This is Bunny. Copy and paste bunny into your signature to help him gain world domination.