The world and European champions turned in a below-par performance to edge out Croatia 1-0 on Monday, prompting renewed attacks on Del Bosque's tactics in Spanish media despite the team reaching the last eight as Euro 2012 Group C winners.
The debate has centered around whether Fernando Torres should lead the line or whether Spain should forego a recognised striker and deploy Cesc Fabregas as a roving forward.
Fabregas scored the equaliser to rescue a 1-1 draw with Italy in the opening game.
Torres started against Ireland and scored twice in a 4-0 success before making way for Fabregas but was largely ineffective against the well-organised Croats and was replaced by goalscorer Jesus Navas in the 61st minute.
Del Bosque said he accepted that people did not always agree with his tactical decisions but said he had no reason to change the way Spain play.
"Perhaps expectations are so high now that people will never be satisfied," the 61-year-old told a news conference at Spain's training base in Gniewino, northern Poland.
"We have gone from poor to rich so quickly that maybe people don't value what they have," he added.
"We appear to be in a period of extremism, of either good or bad, and there doesn't seem to be any middle ground. Football will decide and put us where we deserve to be."
Iniesta, who was man of the match in the Croatia game thanks to his assist for Navas's goal, said the team welcomed criticism as long as it was constructive and it was positive that expectations were so high.
"This is the respect that the team has won and we have to enjoy it," he told an earlier news conference.
"You have to remember that when you win all the time it's hard to maintain the same level," added the man who netted the winner in the 2010 World Cup final against the Netherlands.
"Keeping a winning streak going is hard and gets harder all the time, to constantly exceed our past achievements.
"But that's what we are fighting for and that's why we are in the national team.
"Spain is not a team that does not have difficulties or moments of doubt.
"All I can say is that the team is playing well and we are still in the fight."
Looking ahead to Saturday's quarter-final against the runners-up of a Group D featuring France, England, co-hosts Ukraine and eliminated Sweden, Iniesta said all three of Spain's potential opponents had strengths they should be wary of.
"They all have great players who can hurt you at any moment," he said.
"France perhaps focus more on possession and exchanging short passes, while England are maybe more organised and wait for the counter attack.
"Ukraine are playing at home which is an extra boost that makes them more dangerous."