You're right but this doesn't confirm the reason behind FFVIII not being ported until now
Not to reopen this entire argument btw but nothing they say (yes, even Nomura himself) is accurate. I've read the linked interviews and articles and they're mostly talking out of their asses. "We lost the source code" is PR speak for "the dog ate my homework". I wouldn't be at all surprised if Nomura was told that internally and believed it himself, but I seriously doubt its accuracy. By which I mean I'm sure they DID lose the "original code" or "source data", but I'm certain that had nothing at all to do with FFVIII not being ported until now.
That vg247 article talks about how they reverse-engineered the PC version of FFVII for its 2012 release - this is a lie, even though SE themselves seem to have said this. They attached some code written by a fan to a wrapper to get it running (said fan was involved and is the person responsible for a DX9 driver that got the '98 version of the game running at all prior to the re-release).
FFIX didn't have an initial PC release at all so I don't really know what the story is there. Remember that it came out on iOS and Android before being ported to PC a couple of years ago (and more recently the consoles), so it's a different kettle of fish altogether. They ported the original (may or may not have had "source data" to complement that process).
FFVIII was in the exact same state as FFVII. It had the initial PS release, and then a PC port about a year later - both from Eidos. No other mainline FF was ever ported to PC by anyone other than Square, and if we're going sequentially in terms of titles there wasn't another PC port of a mainline FF game until FFXIII. FFIX was never ported until recently.
SO my whole post is really about saying: there is no reason they couldn't have done the same thing with FFVIII that they did with FFVII. They were in a very similar state (both had PC releases sellotaped together to work by fans, both were re-released in 2012-ish, both had their music replaced by fans, modded to death by fans to make them a more playable experience). The biggest shock is that FFIX was ever ported, honestly. The menu is pure hell but it's insane that was done before VIII.
We can't say for sure why it's taken this long, but I am personally 100% certain it's nothing to do with not having the "original data". It doesn't hold up in any way. The only plausible explanation I can come up with is licensing issues (Fay Wong/ Eyes on Me). I think that's the exact same reason one of the PSP's best selling titles (Crisis Core) was never available to download on the PS Store, even though it would have sold shitloads on Vita.