Camelbacks are popular for mountain biking because it's hard to drink from a bottle if you're on a bumpy road or a downhill. They're not popular in road biking because it sucks to suck, and its easy enough to reach down and get a drink. Also if you're biking when it's really muddy, drinking from a water bottle can be gross sometimes because it gets so dirty.

There are different pedal and cleats because that's the way the economy works. Different company have different ideas and want to keep things different in order to get an advantage over their rivals.