Personally, I share Tormyr's sentiment: It's all about choices, and this is one of 'em. Do you want +2 to your prime stat, or do you want combination Cleave and Power Attack with a bit of Improved Critical thrown in? I like that you might choose not to max out your prime stat right away in order to get that sweet, sweet feat. It makes for a bit more diversity in character design. If you take away that choice, you'll see more cookie-cutter builds, because the "right" choice becomes much more obvious. If you're a greatsword fighter, you put your +2 in Strength and take Great Weapon Mastery. Next time, you'll max out your Strength and get Heavy Armor Mastery. Then you'll start working on your Con.
But it won't break the game if you allow it, and it's not the end of the world to have a few cookie cutters. The one thing I would say is that you should limit this benefit only to levels where everyone gets an ability increase (4th, 8th, 12th, 16th, 19th). Otherwise you're favoring the classes like fighter and rogue that get extra ability score increases.
But it won't break the game if you allow it, and it's not the end of the world to have a few cookie cutters. The one thing I would say is that you should limit this benefit only to levels where everyone gets an ability increase (4th, 8th, 12th, 16th, 19th). Otherwise you're favoring the classes like fighter and rogue that get extra ability score increases.