I don't think so. The reason this thread was brought up is because there have been several recent cases where the difference between a +2 modifier and a reduction in difficulty class have caused confusion. At the very least, the rules need to be clarified.This seems like an aesthetic objection rather than a substantive one.
The most recent example was about robots. The mid tech robots have maximum difficulty tasks they are allowed to even attempt. In the CRB there is a comment that taking longer makes takes easier by applying a +2 DM. In the robot book, it says that task limited robots can use the take longer rules to reduce the difficulty class to be within their capacity. So, is any +2DM the same as reducing the difficulty? There's a lot of other sources of +2 DMs. What if I have two different +1 DMs?
There are other places where Difficulty Level seems to have some innate value separate from the math of target numbers. If that's the case, then it needs to be spelled out. If not, is Difficulty class actually a shorthand that is helpful? Like does saying a Hard task check make more sense than " task check at -2"?
If they are completely interchangeable then, yeah, its an aesthetic objection. But there is obvious confusion about whether they are or not. That's actually substantive.