The only reason I can see for the cables to not work directly attached to the MBP is that the connectors are too wide, thus not being able to sit straight in the USB port. Secondly, the MPS are (imho) known as not the best when it comes to USB port use (there are reported probs with power on the ports, but the cable you use shouldn’t be the problem there).
In my own setup I always hook up a (good brand) powered! USB-hub (2.0) and hook the rest of my gear up to that. Clearly, it’s another point of failure, but with only two USB ports on a MBP, you are not left with a whole lot of options. Since my music (or at least the “request” part of my collection) is on an external HD, I hook that up to one USB port, the powered hub to the other and all my controllers to the powered hub.
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