OP
This comes up all the time, albeit in different forms.There are two types of ways people ask for things in life. Let's call them the Askers and the Requesters. The Requesters do what you prefer - they float ideas, they get feedback, they are expecting a positive response before they actually Ask because they research questions in this way and never do Ask if they expect a negative response. Thus if they get a negative response that goes counter to their research, they are actually hurt by this.
The Askers don't do this. They start by Asking. But because they haven't sounded anyone out, they don't have pre-conceptions as to the answer and they are not surprised by a negative or a positive response.
When an Asker asks a Requester something, a Requester feels awkward because she assumes the Asker is expecting a positive response, as the Requester would do after her research. Meantime, the Asker is just looking for a response.
There are countless threads about this "my DSis has asked me to babysit but it's my DH's birthday, what should I do?" With half the respondents saying, "just say no, sorry, I can't that night" and the other half saying, "wow, how thoughtless, she should have checked first if you and DH had plans"
Requesters will often find Askers rude and Askers will probably find Requesters puzzling (when they don't come back quickly with a straight answer as they are trying to find a nice way of putting it or whatever). Both types are just different. But neither type wants to be mean. 
(There are of course self centred types who strop if you say no, but there are a lot fewer of them than there are Askers.