I can understand why they'd want to force some really obscure settings. Even having settings like that that exist that give insiders that know about them a pretty big advantage (in regards to performance) is definitely an issue. Moreso if they have to spend extra time supporting those settings.
I especially understand not wanting to support DX8. It's fucking old. People only used it to boost performance because it turns some stupid things off.
But the answer isn't to force high settings on everyone. The right answer to that is to make a new fucking advanced video options menu with all of those damn variables so they can be configured (if desired) by end-users. And make them actually change when general graphics settings change, which a lot of them don't currently do.