I think it's a really interesting idea to hide the DC, but show the roll. On almost any encounter you can almost guarantee that if you roll a natural 1 you failed and a natural 20 you succeeded.
I do think though that there would by many times you would be left wondering. I'm thinking of an encounter where you can help some travelers avoid certain death, and afterwards speak with them. There would be a persuasion or deception check about helping them deliver their goods. The possible results could be:

Success = They accept your help, load you up with a locked chest full of their valuable goods, and offer a reward when the goods are delivered intact.
OR They politely deny your help saying they have help on the way already.

Failure = They politely deny your help saying they have help on the way already
OR They accept your help, load you up with a locked chest full of junk, an offer a reward when the goods are delivered intact. However, on the way to deliver the goods, you get ambushed by a group of bandits that steal all of your gear and leave you on the side of the road unconscious if they win combat. (rather than just outright killing you)

There would be almost no way of knowing if you failed or succeeded if any of those 3 were the outcome. I mean if you rolled LOW you could assume failure and HIGH could assume success, but if failure or success might mean them politely denying your offer, how could you know what that means?

Originally Posted by geala
... I reloaded on several occasions when I "succeeded", because I wanted to fail (to get a fight). There are only very very few checks in the EA in which I wanted to succeed 100% of time......

.....but the following fight against the alerted bandits is not more difficult than if you succeeded in the dialog, I find it even easier to a certain extent. The more the player has such experiences, the more he/she may be inclined to accept dice rolls.

So I'm genuinely curious, why would you attempt something that you wanted to fail? I can't remember every encounter, but it seems like at least almost all of the give you the option to "Leave" or if you wanted to fight, there's an option to give a rude response at least. Even if there isn't that type of option to get out of dialog, if you want to fail a check so you can fight someone, why not just attack them afterward?

I think this is where I get annoyed/confused at the way the RP is being taken out of RPGs, and instead turning them into a game where there is a specific narrative you want to follow to get to a specific ending.
I personally feel like having outcome control taken away is one of the best things art like RPGs can do for us. Can you imagine what it would be like if we had no great novels but only "choose your own adventure" books where you could cheat to get the ending you think you wanted? Yuck!