Not buying it. Go to the recent Wenger threads and see how much those recent FA cup wins are valued (FYI, I give him credit for those).
Again, a trophy is a trophy, and Spurs would be better off with any. But let's not pretend as if the importance of said trophies is variable on who's winning it. No one would value Pochettino much better or put Spurs on the next level if they won a bunch of FA Cups and Carling Cups. And like you've admitted, the "springboard" effect is not the norm, but more of an exception.
Wenger has suffered because everyone expects him to live up to the impossible standards that he himself set. I don't value the springboard effect as much as I value the moment of winning a trophy itself.
The importance isn't variable based on who is winning it. I disagree on Poch, if he won a trophy or two then his stock would improve. Discussion of him would shift from a "nearly" manager to one who's won trophy but was hamstrung in the league because there were clubs who had a bigger budget than spurs.
Spurs could win the CL next season without any recent prior trophy winning experience. Pool could do the same this season. The key word being could. If they won a few fa cups and carling cups, there is no maybe or what if there, they did it and winning domestic cups is a record in and of itself. We've won 13 and Liverpool have the most League Cups. Spurs have 8 fa cups
You think it wouldn't mean a great deal to the club and the fans if they won a "bunch of FA Cups" and became the most successful side in the competition's history with 14/15? Same for the League Cup
Also FWIW, we could have pushed on from our two cup wins but summer 2015 was the biggest debacle in our club's history. "Not a single player who could improve us", the only club who didn't sign an outfield player. What happened? Leicester won the PL, Leicester! We didn't even sign anyone in January for crying out loud. If we had just made a few signings then things would be so much different