Robin van Persie and Radamel Falcao fired United into a 2-0 lead, before a Wes Morgan own goal put the home side in complete control at the break.
Marcin Wasilewski headed a consolation goal for Leicester 10 minutes from the end, but Pearson, whose side remain bottom of the Premier League, insisted the result would be of limited importance come the end of the season.
"Games like this game today are, for us, bonus games," he explained. "Our season will be defined by how we play and the results we get against teams in and around us.
"We don't feel that we've given ourselves the best chances of getting something out of today because we didn't do enough with the ball.
"We performed better [in the second half]. We didn't really manage the ball well enough in the first half.
"They're a side with a lot of very good players and I thought they managed the ball very well today."
Pearson expressed a belief that Van Persie's opener should have been ruled out for offside, but was reluctant to dwell on the incident.
"They are honest mistakes," he conceded. "Sometimes they go for you, sometimes they don't.
"It would be wrong of me to be spending too much time pointing out one decision in a game where we played against a side who played exceptionally well.
"It's unhelpful to have things go against you, but that's how it is."
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