Roadies are knee-jerk anti-hydration pack as a rule but they're useful! Especially if there are no known clean water sources on your route (like a few of the mountain roads near me). Also if the water out of water fountains tastes nasty, which it does in Los Angeles.
That's a nice one too - osprey make great hydration packs. And you can put snacks and multi-tools in there instead of your jersey pocket, which is another plus.
I did get a plastic drying rack doohickey for mine - after use, it basically spreads the interior of the bladder so it doesn't stay wet.