>

Keep in mind, you don't have to take out every plane in the bunker.
Just the entrance / exit.
Someone explain the logic please: you build a base underground to hide your equipment from us and go ahead to do a grand opening? >

The grand opening doesn't make sense unless it was basically obvious to other militaries that there's a bunker airbase there. Bunkers by themselves honestly are not as impenetrable as they once were and gain a decent amount of protection today based on secrecy rather than actual protection. This is because once using bunkers to store key equipment became commonplace, bunker busters were extensively researched to the point that most nuclear bunkers even aren't able to withstand modern munitions, especially against an enemy that knows where your base is and concentrates on it. In all, this is more for show as a country like the U.S. could either destroy it or simply damage it to the point it no longer can serve as an airbase and only smaller regional powers that have poor militaries would be threatened by it. >

I wouldn't be so sure. With modern advances in concrete technology bunker busters are again having trouble punching through to properly designed bunkers, and Iran is on top of implementing this technology. It's basically the one technological field where Iran is actually on the cutting edge (at least according to publicly available information).
The arms race between concrete tech and bunker busters has been going back and forth for a long time now, and it's not over yet.