openobex-devel installs /usr/lib/pkgconfig/openobex.pc which needs pkgconfig to properly function. Also, I see for -devel subpkg: Requires: %{name} = 0:%{version}-%{release} The 0 is bogus, and should be dropped... there are no Epochs at work here.
openobex-devel does not require pkgconfig and the 0 epoch stays...
If BuildRequires: pkgconfig not is not added to openobex-devel, any app that BuildRequires: openobex-devel will fail to build when the new "stripped buildroot" version of mock (version >= 0.6) is deployed for Fedora Extras.
If s.th. uses pkgconfig to build s.th. then it should BuildRequires that.
FYI, this issue is being discussed on the fedora-packaging(@redhat.list) list. You probably know my opinion, but if you'd like to chime in, please do so. No final decision has been reached yet, but it does appear the consensus atm is that -devel pkgs with .pc files should Requires: pkgconfig.