Good grief. A PC vs home console back & forth in this thread?
Yes, you would ultimately get the superior product on PC (whether it's straight out of the box - or rather, download file - is another thing, because often you have to fiddle with it yourself, or hope for a fast-working modder to put something out like in the case of FFXIII), but PC isn't for everyone. I'd love to be able to sample a game in its 4k glory, but ultimately I am not very technical in my disposition, nor am I that much of a hardcore enthusiast. Frankly, I have enough going on in my life as well as work commitments to sit down and truly wrap my head around PC jargons. To suggest that primarily console gamers shouldn't get a certain version of a game unless there is a genuine genre or production reason is just a dick-ish and exclusionary thing to say.
Now back to the topic at hand. Is there a need for a FFXIII trilogy definitive edition? No, not really. Would I mind there being one? As long as it only needs a small, rump team or an outsourced studio to handle it without having to exhaust any significant resources and manpower, whatever. I wouldn't buy it, but there's an audience out there that will, so if there's enough demand, give it to them I suppose. Just so long as I get a FFXII HD release first!