I think the effect/power of an additional +1 to an ability, even to abilities that will give you a +1 to hit and damage may not be that powerful. For one thing, most PCs will begin with a +3 bonus in his or her primary attribute. The first increase may be important because for many PCs it will give him or her a +4 bonus. After that, gaining additional ability increases may not pay off.
For lower level PCs, many of the monsters have such low AC and hit points that a party of adventurers will not feel the benefits of any single PC getting +1 to hit or damage. Most melee classes can kill a kobold or goblin with one attack...with cleave...maybe two, and a burning hands spell can take out a large group of the little buggers even if they save. Then, when melee PCs gain deadly strike, weapon damage dice are added so the damage done by the weapon alone is much more significant than an additional +1 to damage accrued by ability increase. Sure, in corner cases, if a PC is alone and must hit to survive, or if the group is fighting an unusual monster that has higher AC and a lot more HP, the +1 to hit will be a small factor that will add to survivability, but in a group of others, not so much.
To me, it seems as though the value of the feat gained will outweigh the ability bonus most of the times, especially if the feats are more substantial than the current ones. Right now, even if I were playing a fighter, I'd want to take cleave and/or improved initiative before adding a +1 to my ability (especially if it doesn't change the overall bonus). In fact, improved initiative is so crucial for spellcasters too. Being able to cast burning hands before anyone else really changes the encounter.
I think that WoTC will have a tough time making the simple PC that only takes ability increases as powerful or as fun to play as the feat taking PC.