I'll give you that. The Texans were void of a traditional 4-3 DE and Williams appears to be the next big thing. Then I would restate that point as Bush was passed equal parts due to a team need and equal parts due to finances/signability.
I agree that finances played a big part in the decision, too. And well they should have!Let's say that Mario Williams and Reggie Bush are both going to go down in history as the best to ever play their respective position, and will be exactly equal in terms of contribution to the team. Let's say also that a top-16 RB (top 50%) can be had for $2 million, and a top-32 DE (top 50%) can be had for $5 million. It makes more sense to grab Mario Williams, then, because a #1 DE/Good RB is $3 million cheaper than a #1 RB/Good DE.
To make a comparison to fantasy football... let's say that Peyton Manning and Larry Johnson are going to finish the season with the exact same VBD this season. I mean, exactly the same, down to the tenth of a point. Who do you draft first? Larry Johnson, of course, because Peyton Manning + a 5th Round RB will score fewer points than Larry Johnson + a 5th round QB. It's not just a question of TALENT AND CONTRIBUTION, it's a question of dropoff and opportunity cost, as well.