Again, you are coming across to me as sounding as if you are objectively correct and having an opinion beyond reproach. Clearly those of us who disagree with you have been pointing out how that is not the case.While you certainly can put more precision into the action you choose to take, who you will attack and with what etc..., it's not an obligation.
...unless you interpret the rules as I, and those like me here, do, you mean? Because, as I read it, you *would* pre-select the target. Because "the action you will take in response to that trigger," to me, includes what you intend to do with the action you are declaring to take. You continue to read it as offering vagueness. I continue to read it as being more succinct in what it is asking of you. Because, and here is the core of my point, when you take a normal action on your turn you declare all those things. When not attempting to Ready, if you just want to shoot the rogue with your bow on your turn, you say so as your action. You aren't noncommittal. You don't say, "I will attack somebody with something."Similarly, you also don't need to select the target of your spell at the moment of taking the Ready action and casting it neither.
"I ready my bow to shoot the rogue if he attempts to move." That, to me, is both RAW and RAI. The RAW interpretation I have already confessed is not crystal clear. Otherwise you would have no valid argument at all. But, RAI? Definitely. I think this is RAI. Plus, that coincides with how readying a spell works. So there is a consistency. And that's a bonus.