I can already tell you the reason they were removed. They were negligible in the scheme of game combat. They were more of a gimmick then having any beneficial effect on the game. So they cut them as skills, there really isn't a way to improve them beyond what they were other than making points in the game that required you to have higher acrobatics or athletics. They really aren't needed to complete the game and that's why they don't need to be a major mechanic in the game. Maybe there will be perks to increase your jump height, probably not though. Also, I personally like the removal of athletics and acrobatics because they always really shattered my suspension of disbelief. In Morrowind you could jump over a fort wall because you could jump so high, they remedied that in Oblivion a bit but you were still jumping a little too high. If they reduced it to a more logical level, then raising your acrobatics would be not worth the effort. Also, those to stats were used to break leveling in Oblivion.
I never cared for athletics and acrobatics and I'm glad they are gone but that's just my opinion.
So, just cut them because they aren't completely NEEDED?
Well, we don't NEED grass. That's not necessary to game combat. Cut that! AI schedules? That just svcks up resources, cut that too. We just need enough AI for people to fight us when they don't like us. Oh, you want to be able to run faster? Nope. Everyone runs the same speed, unless you get this special perk!
It sounds silly, doesn't it? If you make the argument that they aren't necessary to a certain aspect of the game, then you can start removing a hell of a lot. Some people might like to be able to jump high over obstacles, others might like to be able to run faster without having to worry about some perk. What is this, Call of Duty?
I'd say a good amount of people also like the idea of attributes, they allow you to choose a pool of skills most useful to you. How can we improve those? Look at FO: New Vegas. Your attributes actually meant something in that game. You couldn't do certain things if your attributes weren't high enough. Same with skills, too. There is room for improvement on both, and the flaws that some people see aren't reason to completely remove them. That's just lazy.
You don't have to pigeon hole people into not being able to go certain places because their skills aren't high enough, but you can make it more difficult to go about a task in an alternative way. These are improvements that COULD have been made, but instead they just took them out completely.