McGeechan, who led the Lions on the recent tour of South Africa, is better placed than most to make a judgment, having toured twice with the Lions as a player and been involved in a coaching capacity on a further five occasions.
And the 62-year-old believes this year's 10-match tour of the Republic has provided further evidence that the world's most-famous touring team should be backed to the hilt.
"What I would say to those who question the future of the Lions is that unless you have been part of a tour, you cannot fully realise its importance," explained McGeechan, who came so close to repeating his series triumph of 1997 earlier this summer.
"It is nonsense to say that the Lions are uncompetitive. We have provided a superb advertisement for rugby and players in the northern hemisphere, and everyone involved in the game in the four home unions has to buy in to the Lions concept.
"You have seen how seriously South Africa took this series," McGeechan added after the second Test in Pretoria.
"Five or six of their players came back home just so they could play in it and the two biggest events in the game are the World Cup and a Lions tour.
"What we have to ensure on future tours is that they are given every chance of winning the Test series. We need a fair crack of the whip and the structure of the season in the four home unions in a Lions year needs to be looked at hard.
"But there should be no debate about whether such a tour has a future. Speak to any player and they will tell you just how much being a Lion means to them."