The Chelsea midfielder was one of the more surprising omissions when Thomas Tuchel named his 26-man group, having scored a memorable equaliser in the Euro 2024 final in Berlin. Phil Foden, Trent Alexander-Arnold, Harry Maguire and Morgan Gibbs-White were among those also left out.
Palmer, 24, told iD magazine that an injury-affected season at Chelsea was behind the call.
"This season hasn't been the best, but it is what it is," he said. "I'm not crying over a decision you can't change, and I hope the lads make it all the way."
He added that he would follow England's progress from a distance.
"If I'm not doing anything, then I'll watch the matches, yeah."
For a player who has barely stopped since coming through at Manchester City, the summer offers a rare moment of stillness. "I'm going to relax this summer, rest for the first time in 3 or 4 years, before getting back to what I love," he said.
Palmer's season at Chelsea was disrupted by fitness problems and further destabilised by the club's managerial upheaval before Xabi Alonso's arrival. The goals dried up and appearances were limited. Tuchel's decision to leave him out was shaped by that loss of form and fitness in the months leading into the tournament.
The irony is that Palmer arrives at a summer break with more time than he has had in years, precisely because the season that cost him a World Cup place was the one in which he finally ran out of runway. He will return to Stamford Bridge for pre-season in better condition than he ended last year, and with a point to prove when the next window for international football opens.