We probably didn't get Raikou and Entei for the same reasons they weren't a mascot in Gen 2 or why Charizard and Greninja are playable in Smash Bros. over their buddies. Suicune was the one that stood out the most between the three whether due to popularity or other reasons, and for that, it was made playable in this game. Plus, considering we're probably at best getting 20 or so Pokémon, they probably want to spread their choices out rather then give the full set.
Nice to see Weavile. But no one did not expect Mega Charizard X. Because of course and "no one" loves Y. I wonder who's left.
Ok. I guess I can post here since it's been so long since the last post. But the game is out in Japan. Adding Blazeken in August. Which might help the small roster we have so far. A lot of support Pokemon though.