What I like about the Alolan forms is that it isn't so much about "Kanto bias" as it is more of showing players that the Kanto family is still "relevant" and can still fit into the new generation.
2 decades later, there has been a lot of power creep and power seep, and its the Kanto family that IMO has suffered the most from it. Look at Golem. In Kanto it was one of the go to Pokemon if you wanted a solid mineral based defensive wall/tank (just keep it away from water and grass). Rhydon was the other. Then came Johto and Skarmory, Steelix, and Forretress became the new "standards". Hoenn introduced Claydol, Aggron, Metagross, and the Regis into the mix. Then Sinnoh brought us Bronzong, Probopass, and Bastiodon. Rhydon also got an evolution into Rhyperior. Unova gave us Ferrothorn, and made Rhydon better with eviolite. Kalos gave us Klefki and Carbink, and made Aggron even better with a Mega. Then a blast to a parallel universe Hoenn boosted Steelix as well.
Now...with all of these options on the table for you, from a competitive standpoint, why would you want to pick Golem (outside of specific reasons like the "Kanto classic", or a mono team, or just trying to be different, or you really like the Golem line)? What can Golem offer that any of these other Pokemon can't?
Now...based on what has been released officially at the time of this post, the Geodude family doesn't have an Alolan form. Wouldn't this be a good opportunity to dust it off and give old players a reason to use it again? And introduce new players to a blast from the past?
Raichu is in a similar boat. During Gen 1, it had to compete with Jolteon and Zapdos for a spot on the team, and the only thing that made it worthwhile (from a competitive aspect) was Surf (if you could get it). Then came Gen 2, and not only did Raikou and Ampharos enter the mix, but Raichu's own pre-vo Pikachu thanks to the light ball. Gen 3 brought us Manectric, then Gen 4 gave us Electivire. Gen 5 was the introduction to Galvantula and Thundurus, while Gen 6 gave us Helioptile, Mega Ampharos, and Mega Manectric. What incentive was there to play with Raichu now? It was obvious that even Gamefreak realized what had happened, since Raichu got a +10 to its speed in X and Y. That helped a lot (outspeeding stuff such as Salamence and Garchomp is no joke), and perhaps that is why Raichu was one of the Kanto mon's selected for an Alolan form (and given a secondary typing of psychic). The older something is, the less likely someone is to use it unless it really stands out.
Now granted, I don't feel that the Alolan forms picked were strictly for competitive purposes. But I do feel that it was part of it, similar to how the Mega's were picked last gen. A combination of popularity along with ease of use. We don't have an Alolan Arcanine, but do we really need one? Arcanine is pretty solid already! Good stats (nothing below 80), good abilities, and a good movepool on both sides (how many Pokemon get Extremespeed again?). Meanwhile, all Ninetales really had going for it was the ability to summon the sun. And then Charizard Y came and took that niche as well.
I will argue however, that I feel it was a waste that Arbok didn't get an Alolan form. Not because it was the counterpart of Sandslash, but because of its dex entry. Its already been confirmed in the various games and multiple dexes that Arbok has different facial patterns based on where it is obtained. With all the talk of Alolan forms, this would have been the perfect opportunity to showcase Arbok (and also polish off an old mon).