That structure is traditional when 24 teams play in a tournament. The World Cups from my childhood used to be like that.
When there are 24 teams in 6 groups and 16 of them go to the first knockout round, four group winners get a 3rd placed team, two winners get a runner up, and the remaining four runner-ups play each other. Here it just happened that England is in a group where the winner gets you a runner-up from the group of death.
Another possible solution is to go directly to the quarters, with all 6 group winners and the two best runner-ups making it from the groups. This would have made the groups more competitive, but I guess UEFA, as well as FIFA in 1986, 1990, and 1994, wanted those 8 additional knock-out matches for various reasons.
When there are 24 teams in 6 groups and 16 of them go to the first knockout round, four group winners get a 3rd placed team, two winners get a runner up, and the remaining four runner-ups play each other. Here it just happened that England is in a group where the winner gets you a runner-up from the group of death.
Another possible solution is to go directly to the quarters, with all 6 group winners and the two best runner-ups making it from the groups. This would have made the groups more competitive, but I guess UEFA, as well as FIFA in 1986, 1990, and 1994, wanted those 8 additional knock-out matches for various reasons.
