First and foremost, I would like to clarify that the exchange of languages here in italki are not excuses rather these are choices. If I am joining italki, it means I want to have a language exchange. It is my personal choice regardless if it is important to me or not. Probably the word "excuses" in your question meant a different way and it showed up not in a polite way, but I completely understand what you are trying to say. Maybe you should have use the word "reasons" instead of using "excuses"

If you do not have foreign language speaking environment in your country it is very important because you are given possibility to develop and improve your language skills here in italki or in the skype.