i don't quite get the logic.

In order for developers to reach the widest audience, all games they make must follow the least common denominator (Original PS4 and Xbox One). They can't possibly make games that are only playable on the higher end console upgrade. This means that the only things we get from buying the upgrades are:

1. Better graphics

.... and that's it. The games will be exactly the same. The story will be exactly the same. The gameplay will be exactly the same. The voice acting will be exactly the same. For example, the new Forza will run 4k/60fps on Xbox One X, but it won't have any extra cars, the driving won't be any smoother, the game will still be the same.

So is it really worth it to spend hundreds of dollars on something that will essentially play the exact same games the exact same way with slightly shinier graphics? I just don't see it.. maybe it's a good purchase if you don't already have a console but if you already have one, why bother?

It's for higher resolution and better performance....

It's not for better graphics

UNLIMITED POWAAAAH!

And that's it. Why should I buy them? I don't know. It's meant for people who care about specs and better performance. That's not really what interests me. Well, I care about performance, but it's totally fine in the games I've played in my PS4.

Graphics and performance. So a game that is 30fps on XB1 could possibly be 60fps on XB1X.  But I agree.  I would never buy the console a second time.  It's why I haven't gotten a PS4Pro.

The desire of having the last piece of hardware avaliable.
Like they do with phones.
Yeah, is not a rational decision, is like a dickmeasuring

I agree that if you have a FullHD TV, there's little incentive in getting these mid gen refreshes.

Because you are rich enough for a 4k TV and aren't using it for 4K because you have no device or TV channel that uses it. :P

I don't understand that, either.

I can understand the upgrade if you have the resources and time to enjoy it. But I'm the kind of guy who doesn't trade in his consoles. So for me to buy a Pro after an OG PS4 is a bit daunting from a price POV unless I wanted a second PS4 anyway. But in my case, the Pro was my first PS4 which made the decision much easier.

The games will look better on these new systems if you have a 4k TV. Pro sorts out most annoying framerate issues, and I imagine the XB1X will too. Basically if you have 4k TV and buying an XB1 or PS4, may as well get the version that works with your TV best.

Current owners of XB1/PS4 can sell their system or trade it in at various stores as credit towards the upgrade, the same way I imagine some XB1 owners traded in their original for an S to get the HDBR player. (Or they're looking to buy a system for a family member, give the original console and just buy the refresh.)