I mean, they're based on top quality games that, while not a 10/10 in my book, are plenty good enough to earn the occasional 100%. This just adds a few features to it so... I mean if the guy thought it was already a 10/10, I imagine he'd still think as much now.
It reminds me of Mario Kart 8 Deluxe, except that there appears to be less improvements in this instance. A game is rarely going to score lower unless it's a completely botched remaster or something.
I don't think it should be compared based on the previous iteration though, it should be compared based on the other games that are released around the same time. For example, Final Fantasy X obviously had to be compared to different games when it was released in the remastered form. Giving it a minimum of the same score as the original would make much less sense.