No, it's not. "Studies" is not a security-related mechanism and it didn't exist in the past, when fixes were rolled out very quickly anyway for security reasons. "Studies" should not be relied on to be a fix-delivery mechanism, because it just isn't.
This is not even about privacy, it's simple good engineering sense.
I use FF because I care about principles. Otherwise I might as well just let myself be exploited by Google, MS, Apple and friends.
https://news.ycombinator.com/item?id=19825830
(While of course you’re welcome to continue pursuing your issues with it here, your opinions will receive more views there.)
Presumably the testing burden for a preference update using Normandy is smaller, as (and I’m guessing wildly here) fewer things can be altered with Normandy and therefore testing can be simplified to exclude, for made-up example, “the code-signed binary can be executed on all platforms”.