The storyline has not become better or worse until Black/White
Of course only 150 are attainable before the elite four, same with the first gen, and RSE was very similar as well (it was more than 150, but the same idea)!
What's wrong with the radar? It only made it possible to get some other Pokemon, but not all the rest. There are more in the Battle Zone, and some you cannot get without trading.
And are you kidding me that you don't know how to get any of the new evolutions in DP? Mamoswine and Gallade definitely are obtainable before Platinum, but post-game.
Plenty of competetive Pokemon were added. Dusknoir, Mamoswine, Gliscor, Infernape, Lucario, Garchomp, Electivire, Gallade, Empoleon, Ambipom, just to name a few. And HEATRAN. Held #1 in smogon OU a very long time. And if they are, being new evolutions does not rule them out in consideration.