I was wondering if not requiring pickaxes to be boosted to mine the next tier of material is by design. As is, by the time you find lava for a smeltery, you have most likely already found lots of iron and some tin. So, once you have a smeltery, you can make a copper pickaxe, go mine a few iron, make an iron pickaxe, go mine a few tin, and then make a bronze pickaxe. You can go from a flint pickaxe to a bronze pickaxe in roughly 10 minutes if not less. And if you want to make an alumite pickaxe, you just need to mine an obsidian which you can make with the lava you already found, so just a few more minutes for that and now you can mine ardite and go to the nether. Or you can expand your base using a bronze pickaxe to get it boosted and then you can mine ardite with your bronze pickaxe. All depends on if you want to make alumite which isn't used for any recipes, just tinkers' construct tools.
Since I haven't played with boosts required I am not sure on the mechanics. As in, if you boost a copper pickaxe and then upgrade that pickaxe to iron, do you have to boost it again or does it stay boosted? If you need to boost an upgraded pick again then all the better.
Of course, all requiring boosts does is put a bit of a delay before people can mine the next tier of ores. I don't know if that is desirable or not.