I totally agree! I fly from one ATIS to the next most appropriate one, rather than relying on the RPS which is, after all, a "best guess" forecast by a Met Man.
I think you're missing an important aspect of this. Under SERA there is a mandatory cruising level scheme applicable above 3000 ft. The cruising level scheme, if it is to have the intended effect, has to assume that aircraft are flying on a common altimeter setting. With a 3,000 ft TA, that wasn't a problem, the common altimeter setting was 1013. With an 18k TA, there needs to be a legally correct choice of altimeter setting.