I obviously can't speak for them, but from my point of view it wouldn't be so easy because to get all the options MRoogle has it really needs its own page.
Under Search (at the top of the forum) there is already a Google search of MR through a Google Custom search that arn has set up.
With the space that is available in the Search drop down I don't really see how you can do much more than this, which gets back to why I think you need a whole page dedicated to it. Which is exactly what MRoogle provides.