Thorman scored one try, helped create another three and kicked six goals against his former club to inspire the Broncos to a 32-16 first home win of the season.
Smith has now watched his side suffer successive defeats against St Helens and London to dent their hopes of a top six finish in their first season back in the top flight.
"We would have liked him (Thorman) back in our team," said Smith, whose side are 10th with 14 points, five points behind sixth-placed Castleford.
"And I really believe if he had played for us we would have won by a similar margin.
"Without a doubt Chris is a better player than he was when he left us at the end of last season.
"He just keeps getting better all the time.
"He improved the whole time he was at Huddersfield and he is getting more and more experienced now, and it is obviously good for him."
Smith felt his side were in with a shout of adding the Broncos to their list of scalps for the season until they fell away at the end.
"We were still in the mix with 20 minutes to go, when we were only two points behind.
"However, we didn't play particularly well, although we were trying our hardest, and I can't knock the defensive effort of the guys.
"If points were given for effort, we would take both points every week, but we dropped a few balls that we could have done with holding on to.
"We also had some unnecessary turnover of the ball, but I put some of that down to tiredness, and discipline drops off when those things happen."
Smith hopes he will have the influence of injured duo Stanley Gene and Jarrod O'Doherty back at the weekend for the clash against Hull at the McAlpine.
Both players missed the trip to the capital but Smith added: "I shall be keeping my fingers crossed and praying that I'll have both of them available for Sunday."
Last night's defeat continued the on-the-road misery for the Giants, who have not won an away game since beating Halifax with a last-minute drop goal back in April.
* Super League basement club Halifax are to seek a judicial review following the dismissal of last week's appeal over an alleged breach of salary cap regulations.
The club were initially deducted two League points which prompted their appeal.
And the Halifax board were extremely disappointed their arguments were ignored by the appeals hearing.
"Having had the opportunity to discuss the decision in detail, the club remains adamant it has broken none of the salary cap regulations," said a Halifax spokesman.