>But, as soon as you have to take your piece of work and start making little variations and tacking bits on, or running it on different bits of data, or God forbid you want to actually test your code (and make no mistake, code is what you are making), well, it all involves rather a lot of clicking and opportunity for fuck-ups.

This isn't an accurate reflection of where Excel is currently. Excel can run OLAP cubes at this point, which is an exponential multiplier for it's utility as a quick BI solution. Comparisons to programming languages really miss the entire point of why excel is so useful.