I totally agree with this and that’s how Blocs has become what it is today. I spend a lot of time listening to the community, if you use Blocs v1 you would see how user feedback has shaped the app in a multitude of ways.
What would Wordpress, Shopify, Sketch, Photoshop, Tumblr, etc, etc be without 3rd party contribution. The answer, probably out of business (a long time ago).
The API takes Blocs to a new place, beyond what it would ever be if a single company were responsible for its development. It’s a new time for the app that allows others to invest in it to help the community and add features to Blocs in new ways that I either haven’t got round to yet or don’t intent to or literally didn’t even consider.
Regarding Swiper, Blocs offers a build in carousel, what @Lucas has spent his time working on is a more advanced option. The same for the music player, Blocs will get a built in option to play music later this year, but it will be a simple html5 vanilla implementation that does the basic job.
So see it like this, Blocs will offer the basic tools, but there are times when you will want somthing more advanced or not yet available, this is when you have the option to create your own with Bric Builder or save some time and use a Bric someone else spent time making for you. Before the API, you literally didn’t have an option.
We all have our own requirements for a site, in lots of cases, all different. But the API is a good thing for the future of Blocs, why? Because the future of Blocs is no longer solely reliant on a single source.