The way i see it: when it comes to remakes, they always go "HD" cause in their eye, the people only care about graphics and... that's it. "Pretty the game up a bit and it's a must buy!" That works for some, and i don't think there's any issue with that. But it doesn't seem to change the devs focus on graphics in most cases.
If your saying that older remakes of games should adopt new age styles of gameplay and such, i'm mixed on that opinion. Example: if i wanted to play KH1 or 2 and they were forced to run KH 3's engine, that would be a huge turnoff for me. (garbage engine and all XD) Now if you give me a choice between the two, i'd be alright with that. Some things... just shouldn't be touched, as it can be for the best.
But adding content to a game can never truly hurt, so i can support that 100%.