It's very good think when your base is hiden in deep nebula and you can't carry there needed goods all the time. Or it could be really nice if you want to make your base also look a bit better (like Freeports maby).
I really think that only 1 type of base isn't enouth. There are many types of bases in disco. Mining bases, Trade centers, Bars, bse as defence like in New-York, production facilityes (modules construction).
2. Asteroid Miner
This is also good idea. As far as i know not everywhere in system only 1 mining field. You may put that mining turret in 1 of fields in system that's all. Dublin have 4 gold fields, Omega 11 got 3. Most of systems got few fields for mining ore. Also people can't find miners all time when needed and bases not always have ore to sell. So solution is to create mining drone
3. Multipurpose Smelter
This will only need if there will be no more simply gold, diamonds on NPC base. Miners can mine ore, POB's can make it ignots. Like from Uncut Diamonds base can make simple Diamonds, Gold ore - Gold and other. And ready commodity will cast like ore, or even higher as smelter will take time to produse goods and it will need some sort of commodity for production.
4. Assembler
This is too much . If you need something better fly and grab it . But still for hiden bases it will be very good.
5. H-Fuel Production Facility
And this is really not so good. You really want to mix Hellium 3 that casts almost 10k with Deutrenium that casts 1k-3.5k on almost every zoner station just to make H-fuel? And still you will bring Hellium 3 from Kusari because only Okinawa have it. Or mabe some Sigmas also. I think i saw Hellium 3 in SIgma 13 and 19.