Learning a language without its inherent culture is like learning to drive a car without ever being in the car - follow the analogy and you may show pictures, exercises, prompts and what not to teach the driving but without ever knowing the inside of the car, it's engine, gear, why it is the way it is, the learner is bound to run in to bumps.
I think that effective and available teaching aids should be used to enhance learning process. So it doesn't matter whether the material is handmade or virtual.
The dominance of western culture is obviously there but does not influence the language learning part. What might cause problems is the difference between the various Englishes that anybody can bump into. Just imagine a student reaching pre-intermediate level who always had a British ESL teacher but wants to go to a US university. The student in particular will have to take a TOEFL exam which majorly has listening exercises in different US accents/dialects with differing vocabulary. This is the main reason why I do not like using only one set of coursebooks with my students. The other thing is that if you teach about a given culture, you do it in the target language. Right?
