Dilating Door: Actually, most doors are regular doors, except for doors in space – because of the whole opening/closing against pressure issue – which tend to be cog-doors that roll into place. (In addition to the pressure advantage, they’re also relatively easy to open or close when the power is out, by disconnecting the actuator arm and cranking them manually, or rolling them physically.)
There are also doors which melt to let people through, except since they’re actually the power of Sufficiently Advanced Nanotech walls to reshape themselves any way they feel like, and the doors aren’t bound to appear in any particular position, well… (These are mostly the province of the absurdly wealthy who just hate messing up the nice sleek lines of their space yacht with overt door openings.)
And the people heavily into organic technology for houses and starship interiors (see that trope) and other such things generally have “doors” that are actually sphincters, or heart valves writ large. The effect is much the same.
Organic Technology: It does exist in the universe (see, for example, the Gardeners of Rechesh we mentioned back in Flesh Versus Steel and the qucequql, who went an organic-technology route due to their underwater origin, or for Imperial examples, the bioengineering esseli, and the colonists of the planet Kythera (Imperial Core)).
However, while there exist organic fundamentalists (the aforementioned Gardeners of Rechesh), they are crippled by the disadvantages of their technology. Organic structures just plain aren’t that good at a great many tasks, including handling high energies, radiation, etc., etc., and very often, the things that they are good at are different from their inorganic equivalents. A cortexture is a perfectly good organic neural-net computer built out of actual neurons, but it would be wasted performing the same tasks as a regular inorganic processor, or quantum processor less efficiently when it can do the jobs suited for neural-net processing more efficiently. The right tool for the right job, say sensible users…
…such as the esseli and the Kytherans – and the qucequql – who are a more logical lot, and are more than happy to use organic technology where it makes sense, and wrap it up in a nice neosteel hull with a perfectly inorganic fusion reactor the rest of the time. Or engage in bionanotech games with materials and devices that couldn’t strictly be said to be one thing or t’other.