No snark, don't read into a 4 word question. I was genuinely curious about your remark about this.
At the moment %value% is used when the endpoint is being used for the Rule Machine API, for example to set a global variable. Given that there is no other functionality associated with the URL beyond simply triggering the rule, you already know what the URL is unless you are using multiple endpoint triggers for a single rule. So I'm left not understanding what this would be used for.