Champions are the vanilla ice cream of a vanilla ice cream class, there not necessarily anything wrong with that.
The difference is that vanilla is, at the very least, moderately tasty.
The Champion subclass is just bad. It'd be one thing if it was just boring. That's fine; every class should have a "simple & boring" subclass. But it's also underpowered compared to most other fighter subclasses (and even more so compared to other classes).
That said, BG3 gives out free bonus actions and lots of magic items so the Champion subclass will be a less boring and more powerful than 5e RAW. I'd be in favor of Larian buffing the Champion.
