The problem with Open Sound Control is the 'Open' part. It leaves the exact implementation up to each developer.
The choice by Rob Hexler to use a float array ( a combined structure of x, y and optionally z data ) for the XY pads is of course a valid one. OSC is open, so he can do it any way he likes.
It does make it harder for developers to implement a standard way of working with OSC. Basically it means that every one needs to write specific support for Hexler's XY pad version of OSC. That's not such a biggie if you're doing your own custom OSC installation. When you're making a software that needs a standard way to work with any parameter, it becomes trickier.
VDMX bit the bullet a while back, and implemented a specific mode that lets you map 2D XY position controls to a TouchOSC XY pad. We could do the same for XY position controls. We could for instance make a specific OSC address like ..../video/position/xy/values which would accept Hexler's float arrays.
That of course wouldn't help you assigning each dimension to an arbitrary parameter, which is what OP wants to do. For that, it would be better if Rob would just give the option to send each dimension out separately. X and Y ( and optionally Z ) would be then be available as 3 single floats.
Too many bugs and odd behaviors, especially when 2-way communication is enabled.
Yup. We suffer from the same open-ness problem. Coming up with a good implementation of OSC that allows each and every user the freedom to use it in all the possible ways that it can be used, is almost a bigger task than making Resolume itself. We're working on it though, and hopefully we can make some progress once the basic structure of Res 5 is complete.