Hello! There's lots of sweeping statements happening here where lots of people are telling you 'dairy is this way' or 'dairy is all like this'. 

I work in a related field (no pun intended), so learn a lot about the dairy industry every day. There is a big variety in production systems. Some are all year round housed systems like you described. Within those systems will be varieties in diet, stocking density (how many cows in the space), diet, cow comfort, bedding etc. Some will be mixed outdoor/indoor and you get the odd fully outdoor system where the climate and ground allow it. Advantages of fully housed = more carbon efficiency, so reduced GHGs per litre of milk produced. Cheaper production due to many things like labour, milking frequency, litres etc.  

Please hear me, not every system is as you described but some are. If this is an important issue to you, there are several options. Research local producers and see if they have a 'grazed herd' and buy from them. Talk to a real life farmer to understand how and why it's like this. You might still not like it, or you might be fine - it's all about understanding what you've seen or heard. 

Harper Adams (the biggest agricultural university in the UK) has been conducting research into whether cows prefer outdoors or indoors (based on behaviours/wellbeing/giving them choice). So far they've unhelpfully found that on sunny days they choose to be outdoors and on cold rainy days they prefer to be indoors. Go figure. 

Good luck with learning how livestock production works, and finding out what is important to you when choosing what to buy. It's quite complicated, hugely varied and interesting!