Well, one reason is that, unlike in Reason, you don't need a magnifying glass to use it on a higher-res display. Honestly. We are at Reason 10 and there is still no interface scaling or retina support.
A better question is: Why can't I have it in a VST? ReWire is a PITA.
Unless I'm missing something they are selling Europa as a VST/AU and I guess the web version is more of an interactive demo
Woah! I totally missed that. This is a first. And it's free for Reason 10 owners. The product key was already in my account when I logged in. And is has a scalable UI.
I wonder if this is a foretaste of things to come? Maybe Thor next? Please?
It's a nice quick way to try out a demo if you are thinking of buying it.