Two people are a pair and a pair deserves special treatment. Three or more people are a pack and a pack deserves special treatment. Two people act quite homogenic, as it is a natural form of a (sexual) pair who raises offspring and lives life together. Usually, one is dominant, but in some cases, harmony is possible too. When you add the third person, the story changes completely. Politics arise and people start influencing and manipulating each other, both consciously and subconsciously. I'm actually quite neutral on that, because it's probably the only possible way of human interaction. Many proverbs on the subject have been written and you have to admit it's one of the most interesting things going on.
Somewhere in Europe there is a small country called Slovenia. Most of the people don't even know it's there, but those who are a part of it, love it's nature, culture and people. Slovenians aren't obsessed with generals and war heroes, they rather worship their artists, writers and poets. For a country with 2 million people, that's not so hard to understand. Slovene language was only thing that held them together through different times, countries and governments. I think Slovene is beautiful and I'm very proud it's one of the few spoken languages left that still uses dual in grammar.
Dual (as opposed to singular and plural) has been used in different variations by many languages throughout the history, such as Greek, Hebrew and ancient Celtic and Germanic languages. It's still in use in some modern languages, f.i. Scottish Gaelic dialects, Welsh, Breton, but fully functioning as a paradigmatic category only in Sorbian and Slovene. That means that Slovene doesn't use dual only for shaping nouns, it uses dual for forming verbs too.
If you say "we went somewhere" in Slovene, you explicitly tell how many people were involved, because you use a different form of both "we" and "went" for dual and plural. English uses the same verb form for singular too (most cases), and the number can be distinguished either from the noun (using I or we) or with additional explanation. There is no grammatical difference between two or more, only singular and plural exist.
When I first started thinking about this phenomenon, I didn't have an opinion about it, dual seemed natural for me, even though not using dual appears less complicated. As I've grown mature and started noticing life, people and behavior, I also started appreciating dual. Today, I'm a fan.
I like to think Slovene uses dual because of politics. So you can easily express if there was politics involved or not without saying how many people were actually there. The truth is that's probably not the case, but it doesn't matter anyway. My only hope is that we will be able to keep this precious speciality as long as possible in this globalized society where English is the only way to go. Or is it Chinese?