Ruby and Sapphire:
>Natures
>Abilities
>Double battles
>Contests
>Ribbons
>Secret Bases
>Hoenn is so large compared to Kanto and Johto that it makes them look like two halves of one region
>Overhauled the fundamental data structure of the games, future-proofing it for a long time although this came with the cost of the inability to transfer from GSC
>Emerald added the Battle Frontier

Diamond and Pearl:
>Introduced the physical/special split (this is the only positive and meaningful pro for DP)
>Game scenario follows the exact same recipe as RS but with artificially raised stakes
>Retarded lore powercreep and legendary bloat
>Sinnoh isn't particularly bigger than Hoenn and is worse designed
>Engine downgrade
>Retained Secret Bases from RS, but butchered them
>Retained Contests but arguably made them worse
>Platinum copied the Battle Frontier

How can you even pretend DPPt were better than RSE? RSE are probably the most expansive games the series has ever gotten with their sheer volume of content, mechanics and scope compared to RBY and GSC. Meanwhile DPPt just feels like a pale imitation of RSE that follow the same design beats every step of the way but does a worse job with the executions. Honestly DPPt are some of the most bland, safe, generic, formulaic and stale games in the series.