Root was pushed up the order to open after Jason Roy sustained a hamstring injury, and he responded with his second century of the tournament as the hosts secured their third win in four matches.
"Exceptionally pleased, I think he is now the highest run scorer in the tournament," Morgan told a news conference.
"He's scored two hundreds. He's such an important player for us. He is the glue that holds everything together."
Root struck 11 fours and faced only 94 balls in his 100 not out as England strolled to a target of 213 with nearly 17 overs to spare, fuelling their hopes of winning the World Cup for the first time.
"It's probably a side of his batting that has got better over the last two or three years that people haven't seen a lot of, his expansive game," Morgan said.
"He never seems to go at less than a run a ball. You look up, he is going at more than a run a ball and it is exceptionally good to watch. To see him come out and be in this form and continue it is brilliant."
Morgan was forced to leave the field after suffering a back spasm and could be a doubt for England's next game, against Afghanistan on Tuesday.
"It's sore," Morgan said. "I've had back spasms before. We think it is another back spasm. It normally takes a few days to settle down."
Roy also limped off, giving England another headache.
"He had a tight hamstring so he will go for a scan tomorrow and probably it will take 48 hours before we have the results," Morgan said.
England fast bowlers Jofra Archer and Mark Wood took three wickets each as West Indies were dismissed for 212, and Morgan was delighted to have genuine quicks at his disposal.
"I think it's been one of the trends of the tournament," he said.
"A lot of the teams have bowlers who can bowl quite quickly. We are very fortunate we have three guys that can touch 90mph. It's something that we are going to use. It will be a strength of ours."
West Indies captain Jason Holder was left to rue another inconsistent performance from his team, who are sixth in the standings following their second loss and in danger of missing out on the semifinals.
"We were showing glimpses of what we can produce here in this tournament so far and also in the recent past and in the past generally," Holder said.
"It is just a matter of bringing it together for long periods, stringing together a complete game and being consistent."
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