The idea of removing stats from attack bonus is an interesting idea, though it would lead to even more standardization....something that many cried foul at when 4e was released (the idea that classes are too much the same).
Also...it may not be necessary with some other changes. There are reasons primary reasons that the attack stat is so important in 4e.
1) The lack of effect based powers. In 3e, these are called "buffs". Basically they are spells or effects that simply give a benefit, no attack roll required.
In 3e, you could play a cleric with a big strength for a heavy attack stat. You could play a wisdom heavy one who focused on attack spells. Or you could play one with a bit of both, and use buff spells to augment your weaker attack.
In 4e this has traditionally been hard to do. Often hitting is required for both damage and to apply your conditional effects. That means attacking is critical to perform a function on the battlefield.
Now I will say recent 4e has made a lot of improvements here. We have a lot more effect based at-wills and other powers. Heck, there are some very nice cleric attack powers that are pure effect....no attack roll they just add this penalty to the enemy.
2) SAD instead of MAD. 3e is much more MAD than 4e is. In 3e, you need strength for damage (and often to hit), dex for AC, always need some con for living, int for skills, wisdom for that all important will save, cha for.....okay we all know cha was the red headed step child of the lot
In 4e, a rogue for example could make his entire living off of dex. Dex gives him attack, damage, AC, reflex defense, initiative. Con is not nearly as important as it once was, and while having defenses is great you don't deal with the deadly dominates and death saves you did in 3e.
As a second part to this, I think 4e's point buy system leads to SADness over MADness. In 3e, its relatively cheap to get a 14 in a stat. So having a lot of 14's is an efficient use of points. In 4e its more expensive to get a 14, so you are encouraged to focus your points into a few stats.