I'm just ignorant to the reasons of using OpenACS other than to save money. (well i guess there is the simplicity)
You have just partly answered your own question. Saving money and simplicity sound like two good reasons to me :)
Are you suggesting that just because a company can afford Oracle, they should pay for some licensed product instead? If you wanted to use something like Vignette or ATG for example the license fees for these products can easily run into hundreds of thousands of dollars.
And as for simplicity, that's a good thing. Why makes things harder than they need to be. If it's easier to use your development cycles tend to be a lot shorter which means that your software project make actually hit that deadline :)
Then there's the fact that OpenACS is open source as opposed to closed source. I am not going to go into the details surrounding this issue. It's a well trodden path. Start by having a look at www.opensource.org.
