I think the catch rate change is a twofold thing.
1. It makes even people with easy and constant pokestop access rinse through balls, so cha-ching.
2. Severely dampens the ability to grind the 12 candy evolves, I no longer bother with them as I don't think the 3-5 ball trade-off is worth it. This slows down level progress, they seem to be worried people will reach the cap too quickly, but only a small percentage of players (hardcore no-lifers or hackers) are ever likely to get that far anytime soon.
It's a big old fail though, as if I no longer feel like I am progressing in a game, then I very quickly stop wanting to play.
Gym battles are much closer than the old water gun spam, but potions also seem to have a significantly reduced drop rate, which is odd as they aren't monetized. As a guess, maybe they want rampant gym attacks to reduce as well, so increasing how much damage attackers take whilst reducing the amount of healing available should make people more selective in the gyms they choose to attack.