>>39523870 (OP)Easy.
Aside from their egregiously tiny budgets compared to sales (1/32 of expected net profit. More typical "highly profitable" games would use 1/10th expected sales), and known incompetency when it comes to optimization (kanto-less GS solved in a weekend by Iwata despite having zero documentation, Lillie on every map, etc.), it's not the models and animations at all. That's a red herring.
The swap to regional dex only was inevitable. Nearly every other monster catching game out there doesn't have 100% representation every single game. It couldn't last forever, with an ever expanding roster.
This was just the best time they found to do so, when swapping to console would necessitate a major change in transfer method.
Furthermore, with the very significant threat of losing their job to F2P mobile, which TPCi is eyeing heavily after GO, they 1. established the backup plan of Town in case they do get let go and 2. since they kind of expect the death of the mainline games enough to formulate a backup plan, if they were ever going to swap to regional dex only, now was the safest time to do it. If backlash occurs, well, they didn't have much to lose, they were already potentially dying.
And like many other pokemon features, you can tell they planned this ahead of time. There are always minor trial runs of things in earlier gens. Yellow had a friendship meter. FRLG dongle became wireless communication. Poketch had a link searcher, which became C-Gear, which became the PSS. ORAS dexnav and SUMO had overworld-visible wandering wild pokemon.
BW had no returning mon, and (U)SUMO had no national dex, just to test the waters. That's how you can no it's not fully due to any timing or hardware limitations, and it's something they've been planning for a while.
