On the contrary, I consider it absolutely necessary for game balance and therefore a fix, not broken. The situation without combining things like this is what's broken. Game balance, such as it is in 3.5, expects you to have a certain amount of EVERY standard numeric bonus from equipment all at once. Without combining items, this makes using most actual interesting magic items nearly impossible due to slot conflicts and, in some cases, even has slot conflicts between the items you're "supposed" to have. With MIC rules you can actually meet those expectations.
Even if your DM disagrees with that, though, the pre-MIC rules still allow combining items, they just charge a 50% markup on every item but the most expensive in each combination. See adding new abilities.
Have you pointed out to your DM that "One vest, vestment, or shirt on the torso" is quite explicitly a separate and independent slot from "One robe or suit of armor on the body (over a vest, vestment, or shirt)" according to the list of body slots?