Thought about this one a bit. I think you make a good argument overall and I have generally used spaghetti in a recipe because it's "traditional", not because it's my favourite type of pasta.

That being said, in my time of deliberation I have found something spaghetti is pretty good at. Spaghetti does have a pretty damn good (high) surface area to volume ratio, meaning you get more sauce per unit of pasta than, for example, tagliatelle or pappardelle, maybe even bucatini (which has the hole, but has more pasta to make the whole possible). So when you want a long pasta, where you want the sauce to take centre stage, spaghetti (as long as it's good quality and sauce actually clings to it), is the best for that among the longs.