Hi Ania, interesting questions I think that it is a good strategy.
I'm not sure if it is a rule but I notice that irregular verbs are more common in the language than regular verbs therefore we come across them quite often, and they are not so difficult to learn.
I also think that especially for the beginners it makes more sense to learn how to communicate basic ideas (like introducing ourselves, ability to say something about our hobbies, asking basic questions, etc.) Later on, sure, we can focus more on grammar but initially, these more demanding topics can put us off a bit.