I suppose the thing is the Irish value Irish music (even the ones who don't like it that much), and a lot of other people like it too, so there's some advantage for a populist politician in an event like this.The same goes for Black people, with Notting Hill, and potentially for other ethnic groups as well (Indians, Greeks, Italians, Scots, Welsh).
But until English traditions get given the same kind of value and respect, in the first place from the ethnic English, these traditions will continue to be ignored by the politicians.
Anyway the real traditional day for English music has always been May Day, never St George's. (Even if they've switched May Day to a convenient nearby Monday - they'd never dare try that with St Patrick's.)
But I'm sure that if the rules and restrictions on live music were reduced, one of the effects would be a growth in the availability of music with roots in English traditions, and in the number of people appreciating it.
And aside from in a multiracial society, all the traditions feed into each other and produce new traditions with multiple roots.