I'm with you that I pretty much always take a bit of mining skill in a solo play through, but the point investment required to be decent is pretty small. Strength to 2 plus a cigar and three points in miner 69er makes you a very capable miner. Mother lode to 3 as well is a nice bonus but I don't find it necessary. Using rock busters, which is easy enough to do for all dedicated mining days once you're into mid game, effectively gives you a point in mother lode for free, too.
The biggest 'must have' reason for miner 69er I find, if I'm doing a lot of construction, is you really have to go to 4 points (and thus need 4 in strength and a cigar) to be able to one shot dirt blocks. That's a huge time saver if you're building serious foundations or doing underground construction. I'm fairly sure you CAN one shot dirt with miner 69er at 3 but you need a fully modded Q6 steel shovel that rolled lucky for stats. Having the perk at 4 lets you one shot with a Q5 (which you can also forge yourself at that skill level) so is a lot easier to achieve.
The ideal solution there would be variable damage rolls, but that's not something that seems to be on the devs radar. Fixed damage is a major issue with how harvesting works, because the difference between doing 190 and 200 block damage with a shovel, or 90 and 100 with a wrench, is vast. Those last few points of damage basically double your efficiency.