Actually ROMs are a big deal in the Apple II.
There was an overlap in Apple II production and the early non RFI II plus. The difference being the Integer ROMs. Many IIs have had their Integer ROMs pulled and replaced with AppleSoft Roms essentially turned into an Apple II plus. Integer ROMs can be hard to track down and expensive. Typically they are "pulled" from Apple add on ROM cards (Integer version), but those can cost 250-300 alone or more. As time goes on these will be even harder to track down.
Also there were some weaknesses in the Apple II line that were corrected in the II plus around mid 1980. Many pre-mid 1980 Apple II series machines especially II systems by then had these weaknesses repaired using replacement components not "fixes", no one back then cared if you had the original keyboard, they wanted one that worked. Or if the powersupply failed either for fuse or switch (which required drilling out rivets to replace), they simply were replaced. The replacement parts were improved but different.
These days the really valuable systems have original parts, not because they were left broken, but because someone cared enough to fix the machine and not bring it in for service where a part was swapped out, or that someone has gone back and located the correct part and restored the machine.
Enough of my rant, but I'm a car collector and there is a big difference between a 1975 porsche 912 with a VW Flat-4 or one where the engine went and they replaced it with a Porsche Flat 6 changing it essentially to a 911. In that case the 1975 porsche 912 with a VW motor would actually be worth more than one with a porsche engine, because that is the way they came from the factory.
Cheers,
Corey