There are different philosophies in the forum/the company/the user base. Just have a look around.
I for one wouldn’t mind taking the risk in shipping the FP2 with microG and fdroid and no Google services at all. Others think (for good reasons) that this is the worst thing to do, as it will confuse users and it will make the phone less stable.
From what I feel micoG and fdroid are seen as “hacks” (they are) that make the phone less stable and insecure. This is correct, somehow. That again, also depends a lot on the user.
But especially if you want to market the phone to inexperienced users that want everything to be working correctly out of the box and that don’t like complicated learning curves or to wait a while.
Or in short: FP markets the FP2 as a stable Google phone, I don’t think Fdroid will show up as a sysapp soon.
Update: Listen to @freibadschwimmer! I confused the strange abbreviation again. For me, non-Google OS is just easier to remember. I did not understand you were talking about the non-Google OS already.