Glass floors. You may think they look gorgeous, and they keep your building from getting dark and gloomy without proper illumination.
Well, I think they're a terrible idea.
First of all, they won't look that great for long.
Those crystal-clear surfaces will quickly stop being crystal-clear and start being scratched. Unless you want everyone to wear felt slippers or go barefoot or on socks. Maybe even then.
Second, they're dangerous, especially stairs. Glass is slippery because it's so hard and smooth. The harder the soles of your shoes are, the more likely you are to slip on glass. Even more so if the glass happens to be wet, e.g. right after being wiped clean, or if they're outside, and it has just rained.
If you have to walk down stairs like these in shoes like these, you'd better hold on to the handrail. Otherwise you may end up downstairs faster than you'd want to.
Then again, the softer a sole is, the more likely it is to have little pebbles embedded that'd ruin the glass surface even more quickly. So while sneakers may be the only shoes that are safe to wear on glass floors, they're also the shoes that are the most likely to scratch the glass.
Third, if you think that it's only dangerous to walk on glass floors in the wrong shoes, try walking on glass floors in the "wrong" clothes. For example a skirt or a dress. With people standing downstairs, right below you, no less. Remember that glass is usually transparent from both sides.
Now you may ask why I'd walk on a glass floor in a skirt in the first place. Well, it's usually because I don't know beforehand that I have to walk on something transparent to get somewhere, and I've chosen to wear a skirt that day. What do you think I should do, go back home and change into jeans or trousers? Forgo skirts and dresses entirely unless I know for certain what a place looks like which may collide with dress codes?
By the way, grid floors are no better. The last point applies to them as well, maybe not as much, but it does. Also, they're likely to ruin high heels if you aren't careful, and they're terrible to walk on with no shoes on or if the soles of your shoes are too soft and thin.