They may be easier to write but they aren't as powerful. There are a number of examples of addons in sibling comments which won't exist any more because Mozilla wanted to make it "easier".
Even PG has remarked in an essay that success isn't easy - the people who will really succeed are the ones who put in the effort to do the hard things.
Er, designing an honest-to-god specified extensions API is harder than just telling addons developers to run wild with your undocumented and unstable browser internals. Appealing to PG makes no sense here.
> designing an honest-to-god specified extensions API is harder
Of course it's hard. Doesn't mean it shouldn't be done.
> Appealing to PG makes no sense here.
When the argument is being made that it's better to make it easier on Firefox developers at the cost of the user base, the argument made in PG's essay is pretty relevant.
> Of course it's hard. Doesn't mean it shouldn't be done.
What? kibwen is saying that that is exactly what Firefox is doing!
Bear in mind that this is not just "copying Chrome's API", it's copying the base design (how the manifest works, etc), and adding new Firefox-specific APIs on top of it. The whole idea is that most of the APIs addons need will be added to firefox's webextensions API.