Hopefully Trent is mature enough to realise that the decision says far more about Southgate's limited coaching ability and tactical rigidity than it does about what Trent can bring to a team.
There's a reason England haven't won anything for almost 60 years - because the managers/FA/coaching setup is always 20 years behind the rest of the world, and they regularly waste the best talent on offer, or can't seem to fit the best players into a tactically limited system.
Echoes of Sven Goran Eriksson, who couldn't figure out how to get the best of Scholes, Lampard and Gerrard in midfield, despite them being arguably in the top 5 English midfielders of the last 30 years, and amongst the best players in the world in their positions at the time.
England will always find a way to balls it up - it's what they're good at, and why I gave up caring long ago after we couldn't win a tournament with the best group of players you could possibly want in a major tournament at their peak - Ashley Cole, Ferdinand, Terry, Neville, Beckham, Scholes, Lampard, Gerrard, Rooney and Owen. We won't ever get a group like that again who were all at the top of their game for their respective clubs, and a better/more tactically flexible and innovative manager would've won at least one major tournament with that crop.