[alpha_squared]

If you use the "mono" slider, it adds the angled line inside zero for differentiation while monospacing the characters. Presumably, you'd want monospace characters for programming, so I think that's fair.

Your criticism is true for non-monospacing, though I think any fonts suffer from that.

[dragonwriter]

There are lots of proportional fonts that have easily distinguished 0 vs. O (usually, zero is thinner, though often some of the distinctions used in monospaced fonts are also used in addition to shape differentiation.)

[dspillett]

There are people out there who code in variable spaced fonts. Not sure how they can myself but some report feeling more productive that way, and for them this could be more of a consideration.

[cjbprime]

I just started doing this last week! Using Iosevka Aile.