One of RCT3's biggest flaws was terrible frame rate issues as your park expanded.
In 2012, a Roller Coaster Tycoon for the 3DS came out, although it was before any sort of Pokemon, Mario Kart, or such other system sellers, so I'm sure it was overlooked by many.
RCT3D fixed the awful framerate issues, but there were many costs.
The Graphics in RCT3D were mediocre, and the coaster designer was substanceless- extremely limited to basically going up a chain lift, down, turning around, and what almost always ends up as a straight line to the station.
Furthermore, RCT3D severely limited how much could be in your park so that framerate would never drop. Only 2 somewhat competent coasters could fit, and if you had more than 10 stalls the game would stop you right there.
The main point here is that I'm hoping for the developers to set a goal of establishing a solid framerate, but in no way should they have any restrictions constricting our creativity, except the park borders.