Without meiosis there wouldn't be any variation, it's the basic and most important thing to point out.
Explanation: In mitosis their is developement of clones means identical cell. There arises two case
1. If from beginning there wasn't any meiosis; then we'll see most of the organisms alike(mutation may occur)
2. If in humans meiosis stops and we start producing gamete from mitosis; then we'll notice considerable variation (except inbreeding). But it'll be more like blending variation not the independent assortment.