Well I don't know if it's better that's the whole point of this discussion. I am skeptical of it being better because I believe that slow motion undermines the only reason to make a party based RPG RTwP to begin with.
I never said the games were like action games, but RTwP does make combat seem alive and move faster than a TB game. It gives it more of an action like feel. They mix die rolls and stats with player reactivity and reflexes.
And I'm sorry to say this, but the proof that you ask for is in the very paragraph you quoted. It's a system design difference that makes the games inherently different. I'm not sure if you program at all, but when designing any kind of system, everything has to connect with everything else, it's like building a house, the blueprint moulds how the structure comes to life. RTS games have a layer of time embedded into them via distance and resource management. This is why they can have moments of contemplation/planning and moments of frantic action without the need for a pause. Slow motion works in this context because you have a very large map to oversee and lots of shit going on all over the place which is hidden from your view. You need time to move the camera around and find what the hell is going on in a totally different area.
RPGs like the IE games do not have this layer of design built into the system. As soon as you enter an encounter, it's on, and you don't need to focus your attention anywhere else until it's done. This is why a pause is necessary in a real time context, so you can see what is going on and plan what happens next, BUT, once you unpause, everything is hectic again. That's the draw, that's the tension in the system, that is the excitement.
Slow motion has the ability to remove that draw, and that's what I'm skeptical about.