Game developers can pour their heart and soul into a project, and have all the best intentions for the story, setting, characters, game play, etc.
But it's all for naught if ham-fisted publishers extrapolate exactly the wrong message out of success. People didn't buy Halo in huge numbers because they'll buy anything with the Halo brand on it (though, there is a subsection that will), they bought it (probably) because they were long running fans of the series and wanted to see how it all ended.
Now, I guess, we'll suffer through a thousand same-y shooters every year (to go along with all the other same-y shooters released every year), until the series goes the way of Sonic the Hedgehog.
Seriously. Is money the only thing these people can understand?
This is a bad long-term investment strategy. If you really insist on keeping the franchise around, the worst thing to do is to cheapen the IP. This announcement only serves to remind us how much care and attention the corporate suits really give to their titles.