Because these were countries that England oppressed and occupied.

LOL no. The act of Union between England and Scotland was very much consensual and the English didn't oppress the Scottish.

Wales was not a country until recent times. It was only internationally defined as such in 2011. It was always a principality of England.

It's a flag usually assosciated with racist nutjobs. Doesnt have to be, granted, but the usual way of showing national pride and unity is to use the Union Jack.

Then take it back. Fly it at pride parades, palestine rallies, other protests. It's everyone's flag.

Maybe we should calm down on the pride, and instead fly the Jack that promotes more unity

I think people generally fly both. Although I'm not living in England. But when I visited England, I rarely saw St George's cross by itself. I don't think at all, except on a Church of England church (Anglican churches in the UK tend to fly their saints flags anyway, like the Church of Ireland typically flies St Patrick's Saltire or the Union Jack)