An always on clock is a great idea, absolutely. This wouldn't mean the display is always lit up, just a simple analog watch face – time only – with hands that don't intersect in the middle, so there's no constantly lit pixels to burn in.
Raise to Wake: The main reason and the one cited most often is to be able to treat it like a normal watch, which you can glance at without moving your wrist. That's completely obvious and reasonable. In fact, I know quite a few people who don't buy into the Apple Watch because it's silly to have to make a specific gesture just to see the time, and that gesture is always assuming an upright posture. If you're not in exactly the right position and make exactly the right movement, the watch doesn't light up. Some people say it would impact battery life, but two small lines on the OLED display will hardly affect battery life at all.
The better reason, IMO, is to eliminate accidental activations. I find that, more often then raise to wake not working when I want it to, is that it works when I don't want it to. So annoying to catch your watch turning on and off out of the corner of your eye while you're talking to someone at a party, and so distracting to the person you're talking to. It's like a huge nerd flag, the watch lighting up when you clearly didn't want it to. Again, I know many folks who won't get one because of this.
So really, Apple should seriously consider eliminating these two problems that are keeping people from buying their watches, and annoying those who do buy them. If you don't like it, you could always turn the option off. Everybody wins.