That's a pretty cavalier attitude to have when so much depends on the results (and I mean research programming in general, not just the CRU case). Maintainability may not be a concern, but verifiability certainly should be.
Scientists are actually very conservative for most parts exactly for this reason: in practice, it is just not possible to rely on consistent repeatability, etc... When you have an established, widely shared view on a topic, it takes great leaps to break it. Most research is not done to break the consensus, but to reenforce it. That's why today, if you want to show that climate is not caused by human activity, you will need to present data which are not as good as the ones one has now, but which are much, much better. So it is most likely true that if you want grants, etc... the easy way, going along the consensus is the right path.
That may not be how people think science should be done, but that's how it is done in practice in my experience. I think that for most researchers, all this affair sounds like a storm in a teapot. The behavior may look shady at times, the experiment is not always great, but that's exactly why for a new consensus to be created, you need to have better proof than the existing consensus. And yes, politics come into play, yes a lot of it is mean and some of it is not ethical. But this does not invalidate science in general - it invalidates how people think science works.