^Because THAT is the line-up that made them big. THAT is the line-up from when they were bigger than God. THAT LINE-UP IS THE REASON THEY ARE BEING INDUCTED IN THE FIRST PLACE!
I couldn't possibly care less about Eric Singer or (especially) Tommy Thayer. They are just substitutes for the real thing. If they weren't, then Gene would let them create their own IDs (like Eric Carr and Vinnie Vincent did back in the day) instead of trying to pass them off as Ace and Peter.
The last time KISS came into town, they advertised a meet & greet/photo op for $2000. If it were $500 a piece to meet Ace, Gene, Paul and Peter, (and if I actually had that kind of money), I would possibly do that. But, AFAIC, this set up was $1000 to meet Gene and Paul and their sidekicks.
Without Ace and Peter, Paul would still be driving a cab and Gene would still be teaching school in Harlem and KISS would never have been.
THAT is why.