There is no argument here, merely a point for debate.
However I put it simply - if the nation of England wishes to devolve these types of matters from the House of Commons - let those arrangements be made and set-up a devolved assembly (or whatever label you choose) for England, it would seem entirely reasonable.
You do raise an interesting point when you illustrate what the SNP practice is, in absenting themselves from such votes. I believe this approach is principled.
However, how many members for non-English constituencies actually do vote on English issues that might be deemed equivalent to devolved matters?
If there are any - are they "whipped"? Are there specific party gains to be made if this practice remains in place? Does "Calm Down" Cameron or his co-conspirators the Lib-Dems or indeed the Labour party actually benefit from the practice ?