The Aiel never had the tech. They were traveling in wagons, with no Aes Sedai. The One Power was the basis for AoL tech, and part of that seemed to involve "standing flows" or the AoL equivalent of power lines, that allowed normal people to use ter'angreal. It was not just Aes Sedai power that made it so, and anyway, the Aiel did not bring Aes Sedai with them. The Wise Ones as a group arose independantly of any channeling tradition, and apparently took in all female channelers, presumably because that is what women with supernatual abilities do among the Aiel. They seem to throw up more Dreamwalkers/Dreamers than the normal population, just as RJ has said the Seanchan turn out more Foretellers among their damane, and these women are suggested in Rand's Rhuidean experience, to be the forerunners of the Wise Ones, rather than degenerated AoL Aes Sedai.

As for the lack of wars among the Aiel, their society involves constant low-level warfare over scarce resources. When there are plentiful resources, such constant competition might actually spur innovation, but the Aiel barely have enough to survive on, so no. In addition, their culture is not geared towards innovation. The Wise Ones and chiefs (selected based on an acceptance of their past history) have kept them down using mysticism and inflexible traditions and fatalism, none of which are particularly conducive to advancement.

Their channeling is so far behind, not because they are bad channelers (their expertise with what they CAN do suggests the opposite), but because their channeling "institution" - for lack of a better word - was built from scratch, in isolation. Furthermore, with no competition or market forces driving innovation, with the Wise Ones avoiding letting normal people know they even CAN channel, there would be nothing to make them innovate. Even the difficulty of life in the Waste is not much of an incentive, when the Wise Ones run around telling their people that they are there to be punished.