Well, the Taycan is really heavy, too. It helps the Panamera's CoG to put a battery in it. I've seen some people saying that's how they bridged they range-issue while still having instant torque - hybrid Panamera. It's not as good as the Taycan in weight distribution of course, but in any case...
Could you tell us more about what you mean by "Porsche taking advantage for routine maintenance/service" regarding the hybrid? Is it just that the Taycan has to go in for routine maintenance/service less often?
Context: I've done some looking around for stories about the Panamera vs Taycan here on taycanforum, rennlist, and other reviews. It seems the E-hybrid opinion is pretty close to that of the Taycan, but the non-hybrid Panamera is not - the Taycan flatly beats it. That would make sense...