Well, yes, it is a useless analogy... Oh, you meant to say that comparing bridge-building to software development would be a useless analogy? It's not an analogy I made - the point is that just because you can make a cute analogy, it doesn't mean it offers any insight.

> I'm really tired of people being dogmatic about either approach

Exactly - and the implication that I am being dogmatic is a straw man. I am simply opposed to arguments that depend on poor analogies.

Furthermore, all of the bad things that you say can happen if you try to think ahead are as least as likely to happen if you don't, and especially if you have gone in the wrong direction for some time (I know the latter is a manifestation of the sunk-cost fallacy, but it happens a lot on real projects.)