As long as the overhead doesn't increase by much, and I don't think it would knowing mouser, I don't think those of us who wouldn't use the launcher would object to the functionality being there so long as it could be removed.
As for FRR being an almost launcher, I think it's more than that -- at least for keyboardcentric users, it's a ver powerful, fully capable launcher. Between its search setup and the configurable groups, launcher gives immediate access everything I need to get to with minimal interaction -- couple of keystrokes, and I'm where I want to be. This isn't to say I don't understand FRR's obvious weaknesses to those who prefer to use the mouse to interface with their computer -- it takes no stretch of the imagination to see where FRR falls short in that regard.
Personally, I'd rather see unified than separate and I don't even have any immediate plans to use the launcher. As mouser stated, it would be advantageous in terms of the ability to maintain groups as well as frequent/recent access lists between the two interfaces -- as well as other shared configurations. On a day when I'm sitting back and actually using my mouse, if I toggle on the launcher module, all the stuff I'm used to accessing in FRR is right there and vice versa.
There's also the matter of having one application to maintain/support versus having two -- while having one that is merged would be more effort to maintain than either of the two as individuals, I can't imagine it would be easier to maintain them both than to maintain one app.
Plus, having one fully featured application ideally suited to both ends of the mouse v. keyboard debate is surely more likely to grab the attention of the WWW -- offering a loaded hybrid program is surely more valuable than offering two great but limited programs.