The current pickaxes are not bad at being a pickaxe, but it's not the best implementation it could be. This new idea tries to implement MatSci while not being too unfamiliar to old players and harsh to new players.
The new pickaxe will be mostly a frame of a pickaxe, usually already with steel placed in it. If the frame is empty, the player can place a pickaxe modification or 3 bars/cubes of a material for the pickaxe to use it as a head. Depending on the hardness/density of the material, the pickaxe will have more or less mining power (just like the current pickaxes).
The point in this new pickaxe is to incentivate players to upgrade their pickaxes by obtaining more valuable ores to use on it, without having to use the Mining Nano-Fabricator (which every new player just seems to ignore) to craft more powerful tools. It also makes pickaxes more dynamic, by creating an easier modification system where you can place modifications on a pre-existing pickaxe.