Tom - to repeat/rephrase and add a little:
I'm not a a big fan of Par 5s in general, but I've never met a golfer who doesn't like a gentle opening hole, and who doesn't like even more a gentle Par 5 opener. It gives us a chance; and if we make a hash of it we've got no one to blame but ourselves. Now, that kind of opener usually won't make for a 'great' golf hole, but it can play a good and useful part in the making a great golf course, the first step in the journey and first link in the chain.
One of the good points of a gentle Par 5 opener is that it offers a decision-making opportunity right away. Even for me (an average golfer), if it is gentle enough I get to my tee shot and right away have to decide whether to go for the green in two or not -- in other words, I have to feel/sense whether or not "I have it" on this particular day, whether my body/mind will cooperate. The fact that it usually doesn't and that i usually make the wrong decision doesn't alter the mini-thrill of having to make that choice right off the bat. (And if, upon making the wrong choice, the golf hole still allows me to make a bogie at worst, that's a nice bonus -- and a kind of promise that, while I will have to prepare myself for justice and judgement, I can also expect a little mercy and grace.)
The opening hole, it seems to me, is its own "species", different from any other hole in the course. (The 2nd hole can be 'exchanged' for the 12th, for example, and the 5th for the 9th etc etc -- but there can only be one and one kind of opening hole). I think opening holes have to be judged differently. As I may have mentioned to you, the 8th at Crystal Downs is one of the few Par 5s I've ever even liked, let alone loved. But in my opinion, and for my skill level, it would be a terrible opening hole.
(Conversely, for my tastes and temperament, a Par 5 anywhere else on the course should be challenging, like the 8th a CD; otherwise I find them bland and uninteresting, but mostly I feel like the rabbit to whom the architect is non-to-subtly throwing a bit of lettuce.)
Peter