Let me explain:
Adding to hit bonuses without damage to back it up, makes monsters more resilent. I explained it in a different thread, when I discussed the effect of increasing monster damage. If you always hit, your DM might be considering using monsters a little bit higher, thus negating the advantage of hitting better and also increasing the hp of the monster. With themes however, you have an extra encounter power which will make you damage output in an encounter a little bit higher.
I don´t say it doesn´t work, but i guess it should be not needed.
On the other hand, I love the monster AB treshold. It is an inherent bonus, but not front loaded (at level 2, when you just start getting magic items) but a failsafe, if you lose your item or don´t have the right item at hand, you are not much worse, when all other party members can easily hit.
Maybe the monster would be down too fast without the inherent bonus to hit. But a unified increase at that early level is IMHO not needed at all. (Especially the level 2 increase is a major offender... attack bonus of a thief e.g. goes up by 3 points, and maybe 4, if he choses to get lght blade expertise)
So in a rigid system, inherent bonuses are needed... in a dynamic system, effects may be opposite of at you want to achieve!
[MENTION=6673118]Erudite Frog[/MENTION]: no, players never know what level monsters are, that is exactly the point. If none of your players have magic items instead of all having +1 items, lower each monster level by 1 and be happy!