Simpson-Daniel's dazzling first-half try - a weaving 30-metre run that saw him beat four Wasps defenders - underlined his class in Saturday's Aviva Premiership clash at Kingsholm.
The 30-year-old has not played for England since 2007 - a result of injuries as much as non-selection - but he remains among the domestic game's most lethal predators.
"It was a superb finish. It just showed what he can do - it was fantastic," Davies said.
"There were a lot of people around him he had to get through, and his power and acceleration made that try.
"It's fantastic to have a player of his quality. You don't see many like that who don't play international rugby. He has got a lot of experience and he imparts that to players around him."
Gloucester recorded their first Premiership home win since February after fly-half Freddie Burns ran the show for them with a 19-point haul, including conversions of tries by Simpson-Daniel and flanker Sione Kalamafoni.
Wasps left the west country with a losing bonus point after centre Eliot Daly's quality try, 11 points for fly-half Stephen Jones and penalties by full-back Tommy Bell and substitute Nicky Robinson.
It was the Londoners' third defeat in four starts this season. Gloucester, though, will head to newly-promoted London Welsh next weekend having lost just once.
And while the home side laboured at times, they ultimately had too much cohesion for a Wasps side that only fleetingly brought their try-machine wings Tom Varndell and Christian Wade into the contest.
Davies added: "Wasps are a very good attacking team with a lot of quality, but I am a little disappointed we let them back into the game.
"But we are building and that was a step forward today as far as I am concerned.
"We've shown as a team this season that we don't give up, we keep going and we are prepared to grind out wins. That underpins this team at the moment."
Wasps kept themselves in contention despite trailing 20-3 inside 30 minutes, but rugby director David Young knows there is still a huge amount of work to be done.
"We had opportunities to win the game, although I don't think we should have won it, to be honest. We were quite fortunate to be only seven points behind going in at half-time," Young said.
"We've got to respect the ball - we conceded two tries from needless turnovers.
"I thought we lost the physical battle in the first half and left ourselves with too much to do. We seem incapable at the moment of putting an 80-minute performance together.
"We've got to start making sure we are a little bit meaner and a little bit tighter in that teams have to earn everything they get rather than us giving away some soft points."
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