400$ for a 2x upgrade vs 500$ for a 4.5x+ upgrade. With Scorpio you pay 25% more but get over twice as big upgrade over the base console model. It makes more sense as an upgrade. I wouldn't buy a 2x PC upgrade either. 4x is much more reasonable. But this is just me. Some people have more money to spend for more frequent smaller hardware upgrades (PC or consoles).You said Pro was not a good buy for 1080p owners - I disagree. Games run at better framerates, they load faster and new games offer supersampling and better effects. And the upgrade cost is reasonable.
I agree that Scorpio offers more reason to upgrade but that's a given as the jump is much bigger (4x vs 2x)...but then that's going to cost a lot more.
30 fps games are still 30 fps locked on PS4 Pro. There's less fps drops in some games, but most games don't drop that many frames on base PS4 either. If PS4 Pro would have targeted 30 fps -> 60 fps instead of 1080p -> 4K, I would have upgraded immediately. Supersampling is nice, but in current games you can choose either less fps drops or supersampling, not both at the same time. Some games even drop more frames than base PS4 when supersampling is enabled.
I am personally mostly playing Overwatch, and the PS4 Pro version only adds better anisotropic filtering. No supersampling since the game doesn't even support 4K on PS4 Pro. PS4 original is running at 1080p almost 100% of the time (dynamic resolution scaling). A bad example, but an example that plays a big role in my personal opinion about PS4 and PS4 Pro. I have been very happy with PS4 in Overwatch. Frame rate is locked 60 fps and resolution 99% time locked 1080p.
What I am trying to say is that PS4 has been running cross platform games pretty much the way the developer wanted to present them to us at 1080p. Xbox One has required compromises. Now Scorpio allows you to get rid of these compromises. PS4 Pro is obviously also an improvement, but a much smaller improvement at 1080p.