yes obviously about the wet weather, but I would say that 6 months of the year turnout is preferable to none!
all the robots i have seen work on the system that the cows have to come through every so often to access food, some come through twice a day some 4 times. how does it "fetch" them from pasture 
no most farmers don't keep cows that long..... because they are not fit to produce milk after 6 lactations, because holsteins producing upwards of 50l per day cannot get back in calf, or their udders get too large, or they get lame from a very high protein etc diet that they are unnaturally fed to produce so much more milk.
which would you prefer? an ayrshire for example (like one we have) about to have her 8th calf, mainly grass fed, produces 7-8 000l per year and gets back in calf easily, is good enough to take an show at the county show, and is probably good for another 4 calves,
or a holstein that produces 10 -12000l per year,and is knackered after 2 calves. Which is more profitable? which is better cared for? which is happier? (despite the difference in their yields!)
Happy/Unhappy if a cow is bred to produce milk, and fed to produce milk then that is what it will do! I wonder which is under more stress!
Also it depends if you feel that milking cows should be like a factory production line, or not.
Most farmers/herdsmen would say that the milking parlour is an ideal place to manage the herd, and look at welfare. When better to see a lame cow/depressed milk yield/loss of appetite than when they come through the parlour?
How much does a robot care? Also a large percentage of cows that have imperfact udders ( with teats that are not perfectly placed) are not able to be milked by a robot.
If you said to my dh, he no longer needed to milk the cows, but could just manage his cows via the computer he would hate it!
With regards to your last point about re - investment. I agree whole heartedly! 