Interestingly, this method of validation is also used as a tactic for negotiating with terrorists and hostage-takers. But it would be an oversimplification to lump toddlers, bully politicians, and terrorists together since they have vastly different abilities to understand and communicate, as well as limits to how far they'll go to achieve their ends.
I agree with your sentiment that it feels patronizing or insincere when somebody seems to be trying to "validate" my emotions (I'm not being patronizing here, just pointing out that I agree with you!). But I'd bet you and I are prone to thinking logically, and don't usually engage in emotional high-stakes games--two traits you won't find in most toddlers, politicians, or terrorists.
I find that some discussion with the "logical" type can be extremely difficult, because we (I include myself in that category) often don't realise they have an emotional response. I think this is also behind the OP I don't want my emotions to be validated statement. Anything the other does even validation is emotionally rejected (often even a complete surrender, I.e. "you only say I'm right because you don't want to argue anymore).
I noticed this sort of response in myself after getting some communication training. For myself this triggered me to very consciously pay attention to me having an emotional response (obviously not always successful) and the try to deliberately validate the others perspective. Interestingly I find that this also helps me to actually understand the other person more and lowers my "emotional defense response".