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You say people turn on their computers to "get things done", yet complain that features that enable getting things done are "bloat". dbus is tiny and enables processes to talk to each other. Would it be better for each application to implement it on its own? Of course not. Apps depend on it because they need it, just like applications written for RISC OS depend on features of the RISC OS. The only reason why you don't experience dependencies as a "mess" there is only because you don't attempt to rip out core OS features of a closed-source OS.
As for UIs changing between releases, that happened with RISC OS as well. If you don't want change, don't change. But you can't really use RISC OS as your primary platform today.