Yes. The introduction of new specimens is inherent to the concept of “generations.” A new generation is new Pokemon, plain and simple–there’s no separating it. Now, we can debate how often new generations are introduced and the effect the time between generations has on their reception. I can’t think of many good reasons the current 3-year cycle is beneficial for fans outside of the fun of having a steady stream of new content.
Pokemon as a brand hinges on regular expansion of the roster and the new worlds that come along with it. Unfortunately, the Pokemon machine requires such short cycles that Gamefreak can’t keep up and the quality of the games suffers. The same can’t be said for the actual Pokemon designs, though. Modern designs are just as fun and creative as earlier designs. The limit isn’t how many Pokemon can they design in 3 years, the limit is how many Pokemon models can Gamefreak develop, rig and implement in-game in 3 years. This is purely a resource issue which shouldn’t be experienced by a team subsidized by the largest multi-media franchise in the world.
The anti-national dex argument has always been silly to me. From a player perspective, the regional dexes will always be small (400-ish) and no game will ever ask you or even allow you to physically catch every single Pokemon in the nat. dex. Any Pokemon beyond the regional dex are traditionally post-game optional content, or are transfer-only. From a PvP perspective, large amounts of Pokemon will never be viable under any circumstances, and there’s nothing stopping Gamefreak from rebalancing moves and/or individual Pokemon each generation to keep the meta fresh. If you don’t want to interact with 1000+ different Pokemon, you don’t have to. For a majority of the player base, the inclusion of every Pokemon will not affect their experience in any substantial way.
Let’s be honest: SV is only missing 292 Pokemon (28%). Gen 9 lets you, the player, use the most amount of unique Pokemon in the history of the franchise, more than SwSh’s 664, which raised from around 400 to that number through paid DLC after the devs said technological limits and PvP balance forced them to cut what was initially over 50% of the total Pokemon. SV also showed the devs are willing to remove moves that made some Pokemon problematic within the meta. So, with both memory space and PvP issues seemingly non-existent, how much different would the average player’s experience be if SV had those additional 292 Pokemon as transfer-only? The answer is not much, if not better. There should never be a main series game without a nat dex. This is Pokemon, not Digimon or any other franchise. There’s no reason Pokemon shouldn’t try to go above the genre norm.
My personal preferred new Pokemon amount is around 100 or greater per generation. The proposed 50 I’ve seen above is much too small considering tradition. Take 50 and subtract 9 for the starters, 2 for the regional rodent, 3 for the regional bird, 3 for the regional bug, 2 for the regional dog/cat, 1 for the regional Pika clone, 3 for the regional psuedo-legendary, 2 for the box art legendaries, and 1 for a mythical Pokemon. That’s half of the region right there in standard allocation. For most people, the new Pokemon are the main allure to buying the new games. Alongside new generations come new worlds developed around those new Pokemon, and limiting the generational dex limits the new lore that can be created. In the games, Kalos hardly has any mythical lore to its region outside of the war 3000 years ago–why? Because it doesn’t have any new legendary Pokemon outside of the box art legendaries and Zygarde. It does make up for it slightly with the history of mega evolution. Sinnoh on the other hand is a region steeped in lore and mythos because it has so many legends to work with. Paldea is similar. Small generational dexes constrict the overall Pokemon world and prevent regional distinction.
TL;DR: The Pokemon multi-media machine is the problem, not the new generations. Time between generations should increase, and Pokemon should cultivate mid-era games/merchandise to pad time without it feeling like filler. National dex is good, actually. Small generations are bad and only boomers disagree.