Buttler's side defeated Bangladesh in the preceding one-day series but lost batsman Will Jacks to injury and did not call up a replacement.
T20 World Cup-winners Ben Stokes and Harry Brook were absent after Test duties.
"It's a different balance and it's a different kind of feel to the team," said Buttler, after his side was bowled out for 117 in a low-scoring match on Sunday.
"I think we need to give exposure to guys, especially who, in these conditions, also will probably play a part in the 50-over World Cup.
"Felt like a great chance to expose the all-rounders' batting, maybe one spot higher than they may be in a normal team."
Defending the move not to call up any replacements, Buttler added: "It felt like instead of calling up someone else, trying to use some guys who will be exposed to these conditions in the 50-over World Cup."
Bangladesh reached their target with seven balls remaining but Buttler was fulsome in his praise of his bowlers, calling it "an outstanding bowling display".
"On another day we'll probably pick up a couple more wickets in those middle overs and thought we did well to sort of put so much pressure on Bangladesh," said the captain.
Fast bowler Jofra Archer, who has struggled over the past couple of years with back and elbow injuries, was particularly impressive.
He ended with figures of 3-13 to give England a chance.
The T20 series concludes with the third match on Tuesday, also in Dhaka.