I read this, and I say that you should take into consideration this: There is a luck base factor, and that something that talked itself with your exemple. You were more lucky, it has nothing to do with miner having double the rate. The skills of miner is more for going and making mining easier light wise. You see in the dark and such, but any profession can go and get torches. Other then that, the double chance for mineral is kinda low also, which does not affect that much. Excavate is used for DIRT and such only. We cannot use it for other things. Sure... I use it to clear out gravel patches underground, but seriously, with how long it last, it is just a small plus compare to what other things there are.
And when you go and talk about runesmith and such, know this: Miner can only go mining, that what they are ment to do. A runesmith can be used for teleports and all that. Miners are missing a certain charm to it now. Before I got my night vision thing, I use to mine the same amount then normal people, using only torches. Sure nightvision helps, but if people get torches, then they do that same tihng.
So you saying that Miner already does enough money or that they already have what they need is like giving a slap behind their head and laughing at them from behind. They are suppose to be able to mine, and seriously, with the 0.01% chance of getting diamonds from stone and the double drop when, for example, alchemist can simply use the coal that is in big quantity to make a diamond, is making me thing there something missing with Miner. Seriously, when I think about it, if Miner would have the transmute ore thing, then there would be less annoyance.