It would've been more interesting if they weren't "evil", just wrong from our perspective. For example, suppose they needed worshippers to maintain their powers (as was given) but really were using their powers to help and patiently advance their followers towards eventual ascension?
That would've given us a look into what our galaxy might be like if the Ascended Ancients had
acted as shepherds for humanity, while presenting a nice contrast to the Goa'uld as evil false gods, showing that good "true" gods might be worse, which reminds me of this C.S. Lewis quote:
"Of all tyrannies, a tyranny sincerely exercised for the good of its victim may be the most oppressive. It may be better to live under robber barons than under omnipotent moral busybodies. The robber baron’s cruelty may sometimes sleep, his cupidity may at some point be satiated, but those who torment us for our own good will torment us without end for they do so with the approval of their own conscience."
It raises the question of why we'd resort to war instead of having Daniel convince them that they're wrong. But the established plot would serve there, too. We're just as primitive (evolutionarily) as their followers, and obviously the humans in our galaxy need guidance just as much as those in the Ori galaxy, so the Ori would "benevolently" extend their guidance and protection here once our existence became known to them. I'd liken it to a Soviet invasion by people who really are convinced that Stalinism is what you need, or Spanish armies trying to save your soul.
Remove a few of the more brutal aspects of the Ori religion, give the followers a slightly more comfortable existence (perhaps even as sophisticated as the Tolan), and converts would be much more plausible, as would strong dissent over our war against them. The plots would probably be richer as a result, supporting a bit more speculation and introspection depending on the downsides to their path of Origin.
Perhaps this hypothetical, alternate Origin is too rigid, with all of a follower's actions and stations mapped out for them for life. Perhaps star travel is deemed unnecessary. Perhaps disorder and debate is forbidden (because the Ori actually know
the correct answers), thus their insistence on universal agreement. All of this is very close to what was actually portrayed, so maybe making the Ori such obvious
bad guys (lying to their followers, who were merely being used to maintain the Ori's power) was actually unnecessary and even detrimental to the story. Having our heroes have to reluctantly kill "gods" who are advanced, wise, powerful, and good to preserve us as we are would be pretty interesting, like having to wack Thor over a difference in our perspectives.