I think any new language should be designed around options instead of nils. F#, Rust, Zig show different ways to do this, and often any performance penalty can be compiled away.
if/switch being expressions is a simple and helpful idea, languages should allow this.
using map/filter/reduce as the idiomatic way to do things I am less sure about. This can come in handy but also would add a lot of complexity to Go, and in most languages these have a performance penalty.
its important to remember that not all programmers are interested in languages, they just want to get their project done. So being able to hop into a code base and have low cognitive overhead, because there are no mysterious features they have to learn, having quick compile times, and explicit semantics can be really helpful there. That can save you more time than typing less because of generics and meta programming sometimes.