Willey, who has helped England climb to the top of the ODI rankings following their first-round exit at the 2015 World Cup, was among those who questioned the prospect of Archer playing for England at this year's edition when the Sussex quick became eligible in March.
The Barbados-born quick was yet to make his England debut when the preliminary selection was made, but swiftly became a must-pick after acing his early auditions on the worldwide stage, firstly against Ireland and then in England's recent 4-0 series victory over Pakistan.
Archer, an exciting pace bowler capable of deliveries regularly above 145kmh, took advantage of a recent change in English cricket's eligibility rules that allows players to be picked after three years of residency instead of seven.
Now the best ranked ODI side in the world, England are the firm favourites to win the World Cup. "Whether someone should just walk in at the drop of a hat because they are available, whether that's the right thing, I don't know".
Willey, who featured against Pakistan, tweeted that he was "absolutely gutted" to miss out on selection but was "still 100% behind the lads".
Archer downplayed any fears his call-up would cause any friction in the squad, saying he had been welcomed "with open arms" by teammates for the three matches he played.
Dawson, who bowls left-arm spin and can bat as well, comes in for Joe Denly, who couldn't quite impress the selectors with the limited opportunities he got - he bowled just six overs across the two games he played in and scored 17 in the 21 balls he faced.
The Yorkshire-born though got support from England's national selector Ed Smith.
It arrives on the back of an outstanding 2018 with Kent that saw him named the Professional Cricketers' Association MVP, the Natwest Players' Player of the Year, the Royal London One-Day Cup MVP and the Vitality Blast MVP.
The third and final adjustment from the initial squad became a necessity when Alex Hales was discarded after failing two Tests for recreational drugs.
England, meanwhile, will be taking on South Africa in the tournament-opener on May 30.