It's quite easy to explain actually. The evolution process at Pandora occur much later than earth. It's the same as if advance alien race visit earth during stone age.

Eywa has a lot of potential to improve Na'vi lifestyle, but because their evolution has yet to reach that level, it was not put in proper use. Same goes with human race and hydrocarbon, gun powder.

Their respect for nature is synonym to religion. Destroying the nature is almost the same as sun eclipse to ancient people.

Their ability to connect with creatures, well, it's like sixth sense. Unless we have it, we won't know how it feels. It like trying to explain sight to a blind man. Having the ability doesn't mean they must be able to create intellectual device to enhance that ability. Human have sight, but it was not until thousands of year later that we discover how to enhance this sense (telescope and microscope).