A ropey contractor can botch the most basic construction details, and cut corners regardless of the nature of the design. A good contractor will look at the design properly, and if it's true that it's designed to be simple to build, will price accordingly - ie. cheaper than a complex design. What they might not need is a contractor with specialist experience. With simple details - they can look for a contractor who's used to doing bog standard stuff, and can do it efficiently - but that's completely different to a contractor who does low quality work. The way I interpret their words is that they are going to mess this up. It's basically the same attitude that leads to design and build contracts - get an architect to do some nice designs, then hand it over to a contractor to "value engineer" it as if that has no consequence for the design. As if the two things are separate and independent processes. If design decisions are to be made with the aim of reducing costs - then those should happen throughout the process. If that's been done in the early stages, pre tender, then like I say that cost efficiency should become apparent in the prices that are being quoted. If the prices are too high? Redo the design at this point; don't try and make the savings by employing a crap builder.