While soaking nuts and seeds reduces phytates, thus supporting optimal nutrient intake from them, it’s not absolutely necessary to soak all nuts and seeds. You will still be getting a lot of nutritional value from them if you decide not to soak. Phytates in particular bind minerals, preventing absorption. I usually recommend people soak all nuts and seeds if they need support with digestion and assimilation, have a restricted diet or are really depleted, or if they simply just want to absorb as much nutritional value as possible.
Soaking the oats for energy balls or bars will effect the final texture for sure! I usually just use them as is 🙂