Squad selection would have provided the perfect ending to a fairy tale season for the 23-year-old but McGeechan says Cuthbert must focus on the positives following his rapid rise trough the international ranks.
A stunning year in the English Premiership saw the Bristol-born back win his first senior cap in the friendly win over Ireland in August and his club coach is convinced there will be far more to follow in the future.
"Jack's got an international cap now. He's moved forward and he's not in a bad place," said McGeechan, who will be looking to repeat his 2007 Heineken Cup success with Wasps when Bath take on Leinster, Glasgow and Montpellier in this season's tournament.
"As soon as he knew he'd missed out on the World Cup, he rang me up and said he wanted to be involved for Bath.
"He'll be disappointed that he's not at the World Cup but he's in the frame now for internationals in the future. That's great from our point of view.
"If someone had said this time last year that he'd have been in contention for a World Cup place and have already got an international cap, he'd have bitten your hand off.
"He's made great progress and now the challenge is to keeping pushing forward. He's just got to keep looking at his own game and keep developing."
Cuthbert featured in four Heineken Cup games last season, missing the matches against Biarritz Olympique but playing in the home and away ties with Aironi and Ulster.
The 23-year-old, 6ft 5in star had previously made six tournament appearances - five in 2009/10 and one in the 2008/09 season.