Ah yes, the English Question. It used to be known as the West Lothian Question. Nobody ever found an answer.
If Scottish MPs are excluded from voting on English matters, it gives rise to the possibility that a government could command a Commons majority on UK affairs while being unable to put through domestic English legislation. Result: instability.
In reality, there are only two real solutions. One, go the whole hog and establish an English Partliament and an English government, separate from the UK Parliament and the UK Government. Two, stop asking the bloody question.