Kingfrog.... imagine that your MoXS came with NO arps in it, or at least the ones that did basically sucked compared to your T3. And imagine that it's soundset was VERY hit and miss, and it was up to you to go out, and buy a bunch of VSTi's that took considerable skill and luck to 'play nice' with each other.
I doubt you would get it even if you COULD get it at cost...
What do you think 'arps' are?

They are style Parts, plain and simple. Slightly different in concept, but essentially the same. Without them, your MoXS is a MUCH poorer keyboard. As the MS is without great styles.
If you are incorporating those arps in your music, you are no more making original music than if you used a style. You have to make your OWN before you can claim that...
Content, content, content... Any modern keyboard without this is poorer for it.