Another thought I have had is extending the crafting mechanism whereby I am not able to craft an item if there is no room in inventory to receive it. Thus if inventory is full I cant dig any more stone et al.
I wouldn't want to not be able to mine anymore once my inventory was full. It would be too unrealistic and frustrating. You can always do the one thing I keep thinking of doing but never actually do: create yourself a storage room in your mine, and store your ore and stone in chests and crates. Sure, you still have to move your ore and stone back home afterward, but at least you don't have to go back home each time your inventory is full. Now mind you, here's an interesting idea: What if, once your inventory was full and you kept mining, you were given the option to choose to replace the items in one slot with the item you're mining? Maybe it could go further than this by having a selection in the game that states "whenever I mine ore and my inventory is full, automatically replace a slot with stone with this ore."
As for the idea of being unable to craft something when there's no room left in your inventory, I'd rather have direct access to my inventory to provide me with the option of replacing something less useful (say a stack of stone, or a lone stick) with what I wanted to craft. That said, when it comes to workbenches, it would be interesting if they had 1-6 spare slots where you could store crafted items if your inventory was full. Maybe once you get out of the crafting GUI, a 3D representation of the item (i.e. what a block looks like when dropped on the ground or is sledgehammered) could sit atop your workbench for you to pick up. The question then would be "how long would it stay on your workbench if you chose not to take it?" Indefinitely? As long as you state for things to stay before despawning?
In the end, it is annoying to lose a piece of ore to a full inventory, but if your inventory is full in the first place, what's one missed piece next to the 5x64 others in your inventory? When I see I'm close to running out of space, I throw away 2x64 slots of stone as a preventative measure. And once I run out of stone, that's when it's time to leave. But once you have as much ore as I do, even an ore detector can be dropped without a care, because I can easily make thousands more.
But let's keep up with the good ideas. None are bad, and in the end, it's up to the coders to decide whether they get implemented or not. Even if we disagree.