Groove agent 4

I just purchased Cubase 8.5 Artist and would like to upgrade Groove agent SE to Groove agent 4. Now it looks like I either have to purchase Groove agent 4 outright at $220 canadian or just pay $248 Canadian to upgrade to Cubase 8.5 pro. Why don’t we get some credit for Groove agent SE? Why do we have to pay for Agent 4 outright? Doesn’t seem right to me.

Also there does seem to be a lot of extra stuff with Groove agent 4, like a lot more samples (especially presets), how do people like it?