In many ways, greater "user friendlyness" AND greater "flexibility" in software,
can be like "quality" and "performance" sliders for rendering.
If you move one slider up, the other one goes down, and not because of an invert expression, it's very difficult to have, never "everything", but as much of "everything" as possible.
Whereas in either case, there are things which can be done (with some amounts of sweat and ingenuity) to manage to move both sliders UP, without involving plugging another mouse to force both sliders at the same time
In the case of rendering, if you *only* focus on quality, while letting go of a watchful eye even for a second on performance, your render times will exponentially shoot WAY up.
And similarly concerning "human friendlyness", I think it's in that regard that many of the "hi-end 3D" products to an extent may have been missing, and where SI clearly had an edge despite sometimes indeed perhaps hitting certain limitations or walls at certain points.
But such possible limitations were *consitently* and *greately* offset by how much resources (in time, or in not needing rather scarse specialized specialist help, or involving becoming
"system mechanics" ourselves) to get to all sort of results, and were very-much considered as "acceptable compromize", as this "friendliness" combined with a still quite high level of flexibility, also allowed for very creative solutions around all sorts of challenges.
And I think that has to do with the fact that BOTH flexibility AND "user accommodations" were BOTH pushed *from the start* and BOTH equally kept at a *very high priority*, concerning either ICE or the bulk of Soft in general, making for characteristics which even the most technically minded users also greatly appreciated.
Essentially making the 2 sliders go UP, not as far as some others have got one of them individually, (Like Houdini has always been *technically* somewhat more "flexible") but together seemingly quite a bit more than any put together, making things not only fast, but above all *accessible*, which I think is, and should be the key word.
Enough to think that the combination of BOTH may have died along with what "Softimage" (was/is) all about, (as much as it died, even if it still lives probably because of this very subject) which seem-ed to be about pushing exactly that combination, which consequently arguably had, and in all appearances (
for example) -will- probably still have ... the most of "everything" at the same time, until some new (or existing) system is (further) engineered with at least similar priorities, or basic architectural design philosophies.