It's not really metagaming. There are just as many reasons to do it as there are not to. And it's pretty insulting to say that anyone whose Warden did the DR is a clown and a coward.
No, the devs can't make the OGB a "big thing", but Gaider already said he has a more important role than a cameo. And they're not going to kill him off just to balance out the US.
I don't see it as "spitting in the faces of Duncan and Riordan". Heck, Riordan would have LIVED had he not gone kami-kaze on the archdemon.
ANYWAY, to get back on topic...I almost always do the ritual. I'm curious as to what will be done with the OGB, and whether his father will have any impact at all on him/the plot. My canon Warden did it because he loved Morrigan, my female Warden did it because she loved Alistair, and I have a Warden somewhere who made Loghain do it. The only one who didn't was this big pro-Chantry anti-any-non-Chantry-approved-magic extremist.