[Sword & Shield] Question about Sword and Shield

I know not all the pokemon are making it into the main story, but is there any information on whether they will be added in an update after the games release like they did with yo Kai? And another thing is, if they do decide to do that, people didn't get mad when they found out that black and white didn't have any pokemon from previous gens during the story playthrough and those are my second favorite games next to Platinum, but not Diamond and Pearl.

Besides what has been released in the DLC? No. The story playthrough isn't the issue, there is a whole Dexit thread in the Sword and Shield section you can read where people have voiced their opinions on the matter.

The odds of any further updates coming to Sword & Shield are pretty much non-existent, given that a version of the game that comes pre-loaded with the DLC came out recently. They wouldn't do that if there were still more content updates coming.

The difference between Dexit and Black/White is that all Pokemon were still coded into the game in Black/White. Once you beat the Elite 4 and got the National Dex, all of the Pokemon that exist up until that point could be used. In SwSh, some are literally not in the game's code at all.