Although none of my local Apple Stores in Dallas have glass staircases and I've not seen one, I can imagine that there might be a valid reason to replace them with a different material. Maybe they won't withstand the wear and tear, maybe safety. Who knows. But one thing is sure: if the store has more than one level, they offer their customers the CHOICE of using stairs or an elevator. Why? Because the local building codes and the federal government now insist on it.
Imagine if they were not compelled to offer that choice and one fine day you walked into the store and found that the only way to get up or down to another level is to ride the cool, new elevator. It's so cool that there is this long line of people waiting to ride the elevator ... you know, the new modern way of getting up and down without any risk of tripping on the staircase. No effort involved, just push a button. They even gave it sweet name that changes when you push the button: "Auto-Ascend" or "Auto-Descend". Don't you suppose there would be some customers who say, "I'm old fashioned, I prefer to walk." ??
Steve Jobs may have passed away months after his illness caused his influence to diminish; I guess that's possible. But surely there are plenty of high-ranking executives who knew him well enough to remember what worked and what didn't. Maybe they didn't like his insistent style, but they have the help of biographers and pundits all around the world looking over their shoulders now. Yes, there may be pressures regarding China and Wall Street concerns, perhaps even political worries. But I have to think that the corporate ranks include enough people who still remain focused (for the sake of their paychecks, if not their dreams) on something as important as the operating system.
I also recognize the need for R&D to explore new systems for the future, and how we users are the guineau pigs for some experiments. But I can say this with confidence: if Lion was a feature that an auto-maker had rolled out in their newest model car, the owners would have gotten recall letters via certified mail, not Software Update alerts.
OK, your life is not at risk when you fasten your seatbelt to go for a ride on your Macintosh. Lion isn't causing y Mac to catch fire or give me electrical shocks when I touch the keyboard. But I remember what happened when the iPhone 4 was introduced and Steve Jobs was very much alive at the time: people complained that there was something odd going on with the antenna. The company admitted it, fixed it, gave customers a free protective case to mitigate the problem --- all examples of the kind of response that gave Apple the reputation that keeps peope standing in line to get into those stores, regardless what the staircases are made of.