Below spoiler for if you're asking why they changed from their previous "we don't allow any advantages from our cash shop" model.
SpoilerThings change when you hire more people. I'm not supporting all the changes. I also hope some of the items in the shop are updated on release and that they explain the items sometime next week. While stating any changes they made after you know, they were actually tested. Of course, I'm not so sure this is a change from their previous model as they had plenty of items that were quite convenient.
They're hoping for more money and I don't entirely blame them, at the same time they still don't feel like people should feel it's required for them to spend money to be competitive so they tried taking a system from other games (such as EVE). I think they want to use this system to help those who can't spend the money to also get the cash shop items, albeit at a much slower pace. Are they right in making the compromise that convenience items are on the table since they aren't technically pay to win? Not if they do things like making the run from dungeons to your bank twice as long so you'll want the golem banker. However, I'm not expecting this to be the case, I'll judge when they announce the items.
This next one is if you're asking why they would change from their current model.
SpoilerI don't think they'd scrap the model altogether, but I think they will keep a close eye on certain items and even remove them if they prove to be more hassle than they're worth, or if people feel they break the game for those who don't get said items. If rez orbs and repair kits cause a big issue with balance in dungeons they very well might get removed. If the megaphone causes lots of /reports, it might get removed as well, though I actually doubt that.
Also, changing items wouldn't really be scrapping anything because they aren't in the game yet. Ie. they're unofficial.
If they don't announce all the items and explain what's going on before April 10th however, I will also be angry with them since I agree with you on at least one point. People should have the ability to know what they are buying, before doing so.