Instead of worrying so much about a lawn, why not look into natural landscaping?It's a cultural thing, afaik. Somehow (during the previous century I assume) it became important, or a sign of wealth, or maybe even a display of 'I'm living the dream' to have a nice green lawn. Without any impurities of course. And as flat as possible. So it turns into something that is considered aesthetically pleasing as well. I noticed that whan asking people with such a lawn why exactly they want it like that, they mostly remain pretty vague and cannot give much reason to it - which for me is a reason to support my belief it's purely cultural, as it doesn't have much, if any, benefits. Not for the people having to keep it like that, nor for nature.
That last thing bothers me most: for most animal life not bound to soil, a lawn without any weeds wahtsoever is essentially worthless. If you're lucky you'll get some birds able to get the earthworms out but that's it. Bees and butterflies and the likes don't benefit from it. Which is why natural landscaping (or basically, just let nature have it's go at it without much human intervention) is imo always better. We have a couple of acres of land like that: it is mainly left as-is (apart from getting rid of occasional non-local plants and making some pathways through the grass with a mower) and it's a home to a wealth of local plants and animals. The neighbour's land however is dead in comparision, no matter how green his lawn is shining.