You're mistaken, sir. :-)
Although one has the *option* of stating the location in the initial request, it's not required.
Like others, here, have stated, I used to say, for example, "Remind me to call Steve," and Siri would always reply, "OK. When would you like me to remind you?" I'd say "At 3:30" or "When I get home" or something similar. But of late (as reported), she has stopped asking "When...?"
Now that I'm reading the accounts of others with the same issue, I'm suspecting a problem or a change at the system level. (As I'm sure most of you know, our queries to Siri are sent over the network to servers, where our speech is rapidly processed, then instructions are sent back to our phones, where a response is "spoken" to us.)
I can't imagine Apple would intentionally remove this feature, as it's been widely reported that they're hiring entire teams to make Siri do even more and to make her even more "human-like." So, hopefully this is just a glitch. But we need to make sure Apple knows about it.
Everyone, please file reports worth Apple, here:
http://www.apple.com/feedback/iphone.html