Actually, 433 MHz propagation is better than 915 MHz or 2.4 GHz. The only downside is you need a bigger (and more expensive) antenna.
Including Lutron and Kidde radios is clearly a marketing trick to get wider industry support behind Wink. I think it’s a smart move. Combined with Home Depot distribution network this will give Wink a good chance to succeed in increasingly crowded Smart Home space.