Maguire, 33, posted a statement on social media on Thursday evening — a day before Tuchel officially unveiled his 26-man group for this summer's tournament in North America. In the message, the Manchester United centre-back wrote:
"I was confident I could have played a major part this summer for my country after the season I've had. I've been left shocked and gutted by the decision. I wish the players all the best this summer."
His mother Zoe added her own response, writing that she was "absolutely disgusted" and urging her son to "hold your head high."
Tuchel acknowledged the strength of feeling but made clear he had expected their private conversation to be the end of it.
"I was a bit surprised but I respect his personality a lot, I respect his quality a lot," the England manager said at his Wembley press conference on Friday. "He had an outstanding season. I can see the disappointment. I can see the reason behind the disappointment."
He continued: "Still, I was a bit surprised because we had a private conversation and he had the chance to express his feelings, which he did — and this is fair enough because I can see all the reasons why he could be in the squad."
Tuchel explained the selection logic plainly.
"The decision is that we stood firmly with our central defenders that carried us through September, October and November," he said. "Some of them are part of the leadership group that took ownership and set the standards high. It was a decision for these 26 players, even if it feels against individuals."
Maguire has won 66 caps for England and represented the country at two previous World Cups and two European Championships. He did not feature in any qualifying fixture under Tuchel, with his only appearance under the German coming in a friendly. The five centre-backs selected are Marc Guehi, John Stones, Dan Burn, Ezri Konsa and Jarell Quansah.
England open their campaign against Croatia on 17 June.