I would consider actual distribution-native packages of OpenMPT to be more useful. They would of course need to depend on the Wine version provided by a given distribution and integrate nicely.
I am not a huge fan of application-specific cross-distribution packaging that has come into fashion recently. In any case, if the script to generate the package you provided (not in particular only the script that actually runs openmpt, or the generated package itself) is reasonably simple and reliable, if think we might actually be able to include it in the OpenMPT source tree in the contrib directory. There are use cases that it solves.
I honestly do not like step-by-step guides as Saga Musix recommended. All (or at least most of) what should be required to build such packages can easily be automated by a script. Such a script, if written cleanly and clearly, is also a self-documenting step-by-step guide just by itself.
Other than that, I agree with Saga Musix. Providing such bundles tend to get out of date very quickly and require even more things users have to consider to update their software.