I'm A Banana
Potassium-Rich
I can't see a purpose for having any sort of profession or craft skill.
Perhaps there's just a disconnect between those that like the craft/profession skills and my taste in games
Answered your own question, boyo.
Honestly, it has to do with the "forgotten" mundane tier, in my mind. The idea that you start killing rats in a sewer and being spat on by beggars means that your rusty pen-knife will probably break at some point, and you will be forced to engineer a chiv. The idea that you have a family that taught you a medieval trade. The idea that your skill can become your kung fu (I bake with the power of chi! I am such a great tailor my needle can slay fiends!). The magic in a craft performed well (items becoming magical simply because you have a high enough Craft check, rather than necessarily needing to go on seven collection quests).
It's kind of the same reason that gods need to be gods of agriculture and civics in addition to being gods of swords and elves. You need a reason for them to exist, to be rooted in the NPC world, so that they don't just spring fully formed from their mothers womb with the power to shoot divine radiance from their nads.
That said, there are a lot of effective ways to handle this that run a pretty large gamut of styles. I mean, you can go the WoW-ish route of using it to craft magic or superior items (and making sure to include things like exotic diamonds, gold thread, etc. in treasure). You can go the d20Modern route of basically having a job that gives you some wealth and some skills. There's a continuum. "Craft and Profession Skills" a la 3e is just one way, and, very arguably, not the best way, to handle this.