Its not just a matter of hurt feelings, it has multiple problems. If it was just hurt feelings I might agree with you, but it is ambiguous, inconsistent and fails to cover many cases. That is bad UI.
What flags to you suggest people use for Cantonese, Tamil, Arabic and Xhosa?
Why use the Union flag for English? If the language is en-US surely an American flag would be more accurate? You can then use the British flag for en-GB. However, if you offer Welsh you would use the Welsh flag (and presumably the Scottish one for Scottish Gaelic, although I cannot recall ever seeing that) so it would surely be more consistent to use the English flag for British? Even for or generic English?
What flags to you suggest people use for Cantonese, Tamil, Arabic and Xhosa?
Why use the Union flag for English? If the language is en-US surely an American flag would be more accurate? You can then use the British flag for en-GB. However, if you offer Welsh you would use the Welsh flag (and presumably the Scottish one for Scottish Gaelic, although I cannot recall ever seeing that) so it would surely be more consistent to use the English flag for British? Even for or generic English?