It probably comes down to frequency of use, as Eliezer alludes in the next couple of sentences. Shorter words are easier to use and likely to be preferred, but independently of that, the need to refer to an object sized and designed for one person to comfortably sit on it will likely come up more often than the need for a word for "personal recuperation armature, padded interface surfaces, overstuffed, with position-activated leg supports". There's no Platonic ideal of chairness of which reclinerness is a subclass, but there are facts of the social and physical environment in which language evolves.

The category breakdown is arbitrary at some level, but the tendency to prefer more general to more specific categories is real, and so is the association with length. Japanese aoi covers more ground than English blue, but both languages have analogs of "sky blue" -- and they're both longer than the base word.