Wales lost away to both Scotland and Italy and only avoided the wooden spoon with a victory over England on the final day of the championship.
Tour captain Gareth Thomas and fly-half James Hook are the only two players who started against England to be travelling for the Tests in Sydney and Brisbane.
But Wales coach Gareth Jenkins has recalled experienced trio Gavin Henson, Colin Charvis and Michael Owen.
Johnson boasts an intimate knowledge of Welsh rugby after spending five years as part of the red dragon coaching staff.
And he said: "The 18 players they have left at home were all part of the Welsh team that finished equal bottom of this year's Six Nations, so I don't think the new players coming in can be regarded as second choice.
"Welsh rugby has greatly increased in depth in recent years and the team they are bringing out is brimming with international experience and are highly suited to Test rugby.
"Six of this squad has played with the British and Irish Lions and they will be chomping at the bit to have a crack at the Wallabies.
"This touring forward pack will have more experience and be more abrasive than their Six Nations counterparts."
Wales drew 29-29 with Australia last November after an inspirational performance from James Hook, who is set to retain the fly-half jersey for the tour with Stephen Jones at home.
The two sides meet again at the Millennium Stadium this September in game which is expected to decide the winners of Pool B.
Jenkins is using the tour as part of his wider World Cup preparations and Johnson believes many of the fringe players heading to Australia will break into Wales' final 30-man squad.
"Based on the number of changes I think the Welsh coaching staff will use these matches to draw out their best 30 and will be testing as many players as they can before the World Cup," he said.
"They know a good tour in Australia will put them into a strong position to be in the squad in France.
"Come the World Cup, there's a good chance that there will be many players from this tour in their squad in France."
Wales play Australia in Sydney on May 26 and again in Brisbane a week later.