It works both ways for me. I don't think it's right that it should be perfectly normal for players to feign injury to avoid international duty. If you want to play for your national side then you should be properly committed to it and play when you're asked to play, you can't pick and choose. At the same time though I agree that the fixtures are poorly organised and scheduled. Having so many qualifiers and friendlies in the middle of the season is just perverse. Friendlies for one are a waste of time anyway, selecting squads based on league form is part of the fun I think, makes it more exciting at the tournaments to see who bursts onto the scene. Seeing all the players play together in weird little games months beforehand spoils the dream team effect.
I've always thought they should do qualifying tournaments either in the weeks before the actual one, as in do all the qualifying games in quick succession, or have them all in the summers the year before. The footballers would like having tournaments every summer, they always say they don't really enjoy having too long off anyway.