I cannot tell you how much I agree. DP's batch of evos was perhaps my favorite bunch of new monsters, and my biggest disappointment with Gen 5 was a failure to follow that up.
Really, I'm kind of obsessed with this sort of thing, even though I don't really play competitively. It just bugs me when "useless" (broken/imbalanced) Pokémon are introduced when we already have so many that need to be "fixed".
And it doesn't have to be strictly evolutions. I really loved what Platinum did for Rotom, and the hidden abilities really breathed life into the monsters with more lackluster standard abilities (like Politoed and Ninetales, although those two might be a little overkill given how dominant those abilities can be...).
I agree. They should make as many viable Pokemon as possible. If it were up to me, the whole game would add nothing but evolutions to crappy Pokemon to make them worthwhile, plus the starters and the legendaries (six maximum).
I wouldn't mind if they used this opportunity to start balancing stuff up, making defensive play more viable again. They can either do this by adding new elements, for example:
- Passive team abilities, like having Blissey on your team has a chance of curing a status ailment, or having Blastoise on your team raises your defense somewhat and so forth.
- Active abilities or "Limit breaks" for every individual pokemon. For example, even a crappy pokemon like Hypno might be viable if he had an ability to put a pokemon to sleep (without wasting a move slot).
Basically they should start treating it more like an MMO developer, and how they constantly worry about balance and variety.