Most people in NYC rent, and there are many other considerations to make when picking an apartment to move into besides what kind of stove it has. You're often taking what you can get. This law will mean that, going forward, there will be more apartments available that don't have air-quality-destroying gas stoves, meaning there'll be more suitable places for people to pick from.

Also, as the other commenter said, these are apartment buildings. If you burn your apartment down it's gonna affect your neighbors. If you mess up your indoor air quality it's gonna affect your neighbors.

How do you effectively mandate that those building owners are maintaining their gas lines and ensuring they aren't leaking?

This is where it stops being "personal responsibility"

Also you personally can still have gas anyway, you just don't get government subsidized gas infrastructure anymore. Go get your own propane tank or whatever. Go be "personally independent"

Do you have the same opinion on fire escapes? After all, it should be my choice to endanger myself so I can pay a little less in rent.

Because in an apartment building your neighbor's apartment being on fire has a high degree of correlation to if your apartment catches on fire (or gets smoke/water damage).

many people will rent and have no say on what's better for them

For one reason, your decision to use a gas stove affects all the people who live within proximity of you. Everyone’s air quality could be affected, and everyone’s risk of carbon monoxide poisoning increases, and everyone’s risk of fire increases.

No one is an island.

Unfortunately we crossed that bridge a long time ago…

All kinds of reasons. Besides widespread societal misinformation going back to the tobacco lobbyist days, a five-year-old cannot express a preference not to inhale toxic fumes.