My thinking is that if you're not going to wear them as they were made, why buy them? Of course, I do wonder about the sense in this point of view when I'm wandering around in my tweed Bombay pants. I do not feel as dapper as the model at Superdenim looks! :-) (http://www.superdenim.co.uk/feature-detail.asp?featureid=24)
I was after trousers with brace fixtures anyway - wasn't particularly looking for cabourn, but these cropped up at a reasonable price new on ebay.
Would tapering his trousers be that different to those who size down for a slimmer fit than Nigel intended for his jackets? It's an interesting question as to the owners aesthetic preferences and the designers.