DR2: OTR's Sandbox mode is neat cause you can mess around in co-op and it has timed Challenges for you to do that require you to actually level up/get proper items for to get gold medals on the harder ones. Plus they randomly drop Psychopaths on you that scale with your gear, afair, so its definitely not just "play until you get bored". Better than vanilla DR2.
Uncharted 4 on Crushing is balanced around being done on a second playthrough and onward, not on a first run. I did Hard mode on my first run and had a blast. Planning on doing Crushing at some point, which is more than I can say about my urge to replay 1-3 after I was done with those.
Curtain Call is great until you realize that, like the previous game, there's a dearth of content to actually besides just playing the songs and the tracklist for some of the games isn't exactly stellar. The DLC isn't great either, and it gets specially jarring when you buy a song from a non-FF game and fight FF enemies / bosses inside the track because they couldn't be bothered to make new enemies to go with the tracks. It'd be one thing if it sold itself purely as a rhythm game, like the Project Diva series, but it adds all these extra features like experience, leveling, rhythmia collecting, and the quest system that are neat, but don't go deep enough into satisfy the itch/hunger that they bring by being there.
Ok, that sandbox mode sounds cool.
I'm about halfway through my first run in DR2: OTR, finally got at least 1 stat in speed and the game is much more pleasant. I'd imagine at 3 stat points in speed the game feels great. Game is mixes between good and not good. I'm just kind of speeding through it because the story is pretty much the same and the game is the same so might as well blow through it quick, but also because I've almost completely given up on saving survivors. This is the worst survivor DR games in the series imo. If the survivors are near the safehouse mall, or I have a nearby car, I'll save them. Otherwise, I'll just take the join up points and not even try to get them to the safe house because they just fucking die in OTR. I've had so many survivors die and I've never had this issue in DR1/2/3. It's really frustrating and is slowing down my leveling since there's not enough psychos spawning yet and I can't get the survivors back, so I'm only lvl.13 now halfway through the main cases.
I have a feeling that survivors speed up with the MC's speed up, so maybe at more speed stats they'll be able to outrun zombies and not consistently get caught 500 yards away from you if you're not baby-sitting them. Also the mechanic where they take friendly fire when you're trying to free them from zombie grip is utterly stupid.
It might be my poor memory but I feel like DR3 had 2 major improvements that makes going back tougher, 1 being the ability to save your favorite weapons so you don't have to keep collecting and remaking them, and 2 being having more safe zone locations so you don't have to take the survivors all the way back to the starting safe room which can be all the way across the entire map (though at least DR3's cars can speed that up).
Still OTR is fun. Will finish it and it'll be enough to hold me over until DR4.
With Curtain Call, I don't mind the DLC songs being set to FF graphics. I don't really care about the graphics or the leveling since like you said it's all shallow and it never means anything. In fact in DQ Theatrythm, I never found a reason to even mess with the skills or equip items, as long as I was higher level than the song I'd win. Curtain Call seems the same. My only disappointment is I think that the DLC songs don't factor into quest mode, which sucks because there's no point in playing single song mode instead of quest mode unless I want to play a specific song. Would be nice if you could integrate the DLC into quest mode for the filler in-between tracks while going through dungeons.
