For me, there's nothing overly controversial in his squad selection. Eze over Grealish, perhaps, but if neither are a set starter it makes sense to go with the player in form. There's always been niggling reports about Grealish's professionalism and application in training, too. Generally speaking, England has a strong squad. My experience of international football suggests to me at least that we do not have a good enough keeper or CBs to make us favourites, but if the midfield and Kane all turn up then we're capable of beating anyone.
It would benefit England to play a decent team and win in the earlier rounds of the tournament. Under Southgate England typically lose when put up against the first good side they've come up against. Mentally it's something that needs to be banished. A bit like in 96 when England battered the Dutch. Something similar would be rallying. Not that the fans need any more confidence, but it should be for the players. The likes of Konsa, Kane, Rice, Shaw, Saka, Pickford, etc, haven't won much (if anything) to date in their careers, so putting a marker down early feels important.
The biggest source of joy at the European Championship is seeing a fat, half-naked, Brexiteer, only wearing a Barnsley tattoo, in a state of disbelief and tears, as England crashes out on penalties.