Agree with what Dennis says. Always start in AC3D and use several other modelers/programs for any additional stuff that I can't do with it. For example ... if I need more control of texture mapping will use UVmapper.
The ability to import/export in the .obj format makes it very easy to move things around. Also, as I work in VRML, always do my final export from AC3D. While AC3D does not allow the addition of all the interactive VRML nodes, the code it exports is very clean compared to some of the other (often more expensive) software out there.
There will always be features that I would like, but they probably are not things I would use every day. I also think that some of the *simplicity* you talk about comes from some good design and thought that Andy and the rest of AC3D team have put into the software.
For example, I think the new hierarchy control in AC3D v6 is probably the best I've seen anywhere (posted about this elsewhere )
griff