Well you put up the three bullet points making it sound like that these are the only options, sorry that I misunderstood you.

> You ask "why", well look here at the features the open source tool we use provides: https://matomo.org/features/

That's more about about why one should use Piwik instead of a different tracking tool.

> shouldn't we try to make the best website we can?

Sure. And IMHO the benefit of not having a banner / tracking outweigh the cons.