Iterators are very nice addition, even with typical Go fashion of quite ugly syntax.
I didn't study the reason why Go chose this way over others. I do know they've considered other ways of doing it and concluded this one is best, based on complex criteria.
People who make value judgements like this typically ignore those complex consideration, of which playing well with all the past Go design decisions is the most important.
Frankly, you didn't even bother to say which language does it better or provide a concrete example of the supposedly non-ugly alternative.
Go had both generics and iterators from the get go. Just not user defined ones.
Thus it is obvious that the creators of the language always saw their need for a simple and productive language
There is close to zero practical need in user-defined generic types and generic functions. Go 1.18 opened Pandora box of unnecessary complexity of Go specification and Go type system because of generics. Users started writing overcomplicated generic code instead of writing simple code solving the given concrete task.
Generics also allow to write some data structures that would be useful e.g. to speed up AST parsing: writing a custom allocator that would allocate a large chunk of structs of a certain type previously required to copy this code for each type of AST node, which is a nightmare.
This sounds like a good application for Go interfaces (non-empty interfaces). The majority of generics Go code I've seen could be simplified by using non-empty interfaces without the need of generics.
But what can we do against of this? This what I think: - stuck to use Go 1.16 - fork Go 1.16 and continue develop lang from there - learn OCaml... - give up and consume what these people decide to add to lang next and everytime feel disgust