You do realize that 4e has a very specific power curve in regards to Enhancement bonuses? Even level monsters and PCs hit on a 10+,
The curve is not like that.
Originally, PCs started just ahead of the curve. With a +3 attribute bonus, at level 2 with the +1 something, if you're an implement user, your hit will be +5, and the defenses you are hitting will be 14, giving you 60%.
The collecting wisdom, however, makes characters with +4 attribute bonuses, and starts with some form of accuracy booster, for another +1, giving 70%.
At level 30, using the original progression, 15(lvl)+7(att)+6(enh) = +28, 42, meaning you need an 8 to hit, putting you at 45%. But by that point you have such easy access to bonuses to hit and combat advantage that you're not far behind.
Of course, now, with an extra attribute bonus, and +4 from accuracy boosting feats, this implement user would be at 70% again.
The game's '50% to hit' rate only existed at level 29. Every other level, the hit rate was some higher number.