Macro-Evolution is bad Science due to the fact that it doesn't hold up to the the definition of Science very well. Macro-Evolution is based on inference, guess work and huge leaps of faith in order to arrive at mans desired outcome.
On the other hand, Micro-Evolution is what we observe throughout history, merely adaptations of an organism or creature to suit it's environment or habitat. Micro-Evolution is Scientific, logical, definite and relevant in the subject of Science.
Macroevolution and microevolution are the same thing. Macro is just more of it.
When someone accepts microevolution but not macroevolution, its like saying its possible that someone can clap their hands once but its impossible to clap them 100 times.
A reasonable person would accept that microevolutionary changes would add up over time. Perhaps creationists thinks that God steps in and says "whoa whoa whoa...all you microevolvers gotta stop that right now before you create a new species!"
If God gave us the tools for curiosity and critical thought, I think He would be disgusted at people who deny using these tools in favor of some man-made book filled with lies, contradictions, and absurdities - a book that portrays him as a pro-slavery, vindictive monster. God would surely hold in higher esteem those who endeavor to understand His creation over those who constantly lie to themselves and others in order to avoid that understanding.