Won’t I need reading glasses anyway at some point? Why choose Monovision if this is the case?

Yes, it is likely that your need for reading glasses will increase over time despite monovision but think of it as a magnifier sitting in your eye. It will always be more useful to have it than not. Even later in life, it will be useful to spot things such as prices on the supermarket shelf/dashboard/cell phone even though you may need glasses for small print.