- nouns have no gender !!!!
- conjugation is extremely simple (only one variation for 3rd person singular for most verbs!!)
- tenses are limited !
- vocabulary is 40% French-Latin and 60% Germanic, most of Europe and America can use the subset they prefer
- the writing is latin, simple to learn, complete enough to describe well the sounds
- the native community is immense, with a large interesting cultural body of work, making it interesting to learn
- it's easy to start communicating but it can be extremely rich in higher levels of language: you start talking quickly and then can move to beautiful structures later: there is a quick reward and a long term reward
There is nothing unfortunate it became default, there is simply no better lingua franca today. We could try Japanese or Chinese, Hindi or Spanish, but they all have way more quirks and way less qualities !
I strongly reject people saying that English became default by historical chance, it could have stayed French, moved to German or Spanish, it SHOULD be Chinese, but all of them are too hard for adults to learn as quickly as English and never as rewarding. Just think of the time it takes to learn an ideogram-based writing system, all that to end up able to read only communist propaganda or very old poetry for instance...