This issue really gets on people's nerves doesn't it? I certainly don't 'speak as though everyone has 5,000 credits at the ready', but it's clear that a fair few people do have a lot of credits at the ready, some of whom were no doubt waiting for an event like this. You feel that someone that committed should indeed be able to unlock a load of stuff straight away, I'm simply saying that I can see why Blizzard wouldn't want that. It devalues the event for those players and it will certainly make the items dramatically less rare. Further, once they set the precedent, far more people will save their money up for the next time around.
I tend to find myself advocating for Blizzard in these debates not because I think their system is completely right, but because I find their opponents to be blindingly over the top or downright unreasonable in their criticism.
It is amazing how much flak Blizzard are taking for doing things that are... so... average within the games industry today. These are, at the end of the day, cosmetic items that have no impact on gameplay, and the items are generally high quality. I just can't get that upset when games like Call of Duty, Halo, FIFA, and Battlefield all feature gameplay affecting items in their chests/chest equivalents. Halo 5's chests (or REQ packs) give you cards that can be redeemed for a single use of a single weapon, powerup, or vehicle. It's straight up pay to win, and, unlike in Overwatch where the loot drops are well designed content, they represent content that costs the developer nothing to make.
Overwatch doesn't get a free pass because there are worse things out there but it does make it hard to listen to the more extreme accusations in this thread. I actually think that these RNG style loot chests need to be heavily regulated at a government level, if not outright banned... but I don't consider Blizzard evil for doing a fairly muted version of what everyone else is doing.
Personally, I'd like to see them remove duplicates altogether, though this would probably necessitate some adjustments to how many loot boxes you got, or how many items come out each time. I also think you ought to be able to buy currency from the store (at a pretty sharp exchange rate, around the 50 coins per dollar mark). Those are the two changes I would make if I were Blizzard, and I think they're fair without radically adjusting how quickly/cheaply you can get stuff. They may end up doing these things and they may not. Either way, I can live with it, because they'd make very little difference to the way I play the game.