I think what Peter is saying is that a package manager would be very useful for installing non-"atomic" applications, such as some of the ones he ports from Unix. As a Unix user I can see where he is coming from.
With most native RISC OS apps though the situation is less clear, since many of these are self-contained, and RMEnsure already deals with modules.
The main problem that this solves is with shared dynamically linked libraries, something that we don't really have on RISC OS, although the Shared C Library achieves similar functionlity by using a module, with functions invoked by the stubs that are statically linked to the program..
If proper DLLs ever do get implemented on RISC OS, some sort of package management system will become eessential.
So perhaps a package manager (and DLLs) are worth having if only to aid porting from other platforms.
I would hate to think that it would encourage programmers to move away from the application directory concept, with everything except modules kept together. It is one of the strengths of RISC OS.
But on a minority platform like ours, it makes sense to make porting from elsewhere as simple as we can.