That why I would change it to be a predictable system. It could move around the map in a predictable way at set times. There are a few ways that you could set it up that could be interesting and still be predictable. You certainly could do spot A gets a random selection of power weapons every 2 minutes, but I would rather see it setup that there are say three main spots on the map where a power weapon might spawn. So initially spot A gets rockets, then a 2 minutes, spot B gets sniper, and after 2 more minutes spot C gets sword, and then it rotates through those spots every 2 minutes with those weapons till the end of the match. Still predictable, the spots don't change but your team would have to set up differently to secure each weapon.
In practice I don't find the random factor of global ordnance to be much of a deciding factor. I think everyone has an example like yours, but as a percentage of games I think it is pretty low. Also over many games it balances out, as is true with a lot of Halo 4 mechanics. I think the problem a lot of people have is they don't think that way and when those moments happen they impact in a very strong and suck-y way so they stick in your head. People don't consider an aggregate of experience over a set of games other than 'hey, that was annoying'.
Camo shouldn't be in loadouts, but I don't think it should be in any mp game ever in any fashion.
I still find the only thing that really bother's me is lag, I wish that was an issue that could be tackled with better results.