Smart move in my opinion. Won't be a popular opinion but I think he is highly unlikely to ever reach England quality and therefore has more chance of playing international football with Wales.
I think with us being in L1 for so many years we have forgotten what true England quality looks like. Brooks has potential to be a very tidy player, but when you recognise that Dele Alli is only a few months older than him, it might make you realise how far away Brooks is, in real terms.
In his position alone, there are plenty of players under 25 that are way ahead of him (Redmond, Rashford, Murphy, Ali, Oxlaid-Chaimberlain) and really there quite a few more, I think it makes perfect sense from his point of view.