I always had a stong letdown as well as contractions in the beginning as well with nursing. I also had phantom movements for about 6 months with Devin where it felt like I had early stage pregnancy movements inside my belly.
I never had any cracking and bleeding, but I always use a lot of lanolin in the beginning when my nipples are getting toughened up still and also really dry my nipples off before putting them away. It was slightly more uncomfortable for me with Coop, but I used the APNO my dr prescribed and that did the trick. It should never be painful though, and if it is, there is most likely something else going on like bad latch, or cracks etc.
But again, each woman is different. We all have different tolerance levels for pain and different levels of milk supply, and different levels of tolerance for the amount our bodies can handle in producing the milk as well as sleep deprivation. Plus, nursing full time, especially for a mother working out of the home who has to pump, is a huge committment and the sacrifices you have to make sometimes may not be worth it to all woman. Some people aren't willing to put in the work. Some are, but just can't make enough milk etc. There are so many different angles to a successful nursing relationship.
In the end, all of our babies get fed and loved on one way or another and that is all that really matters in the big scheme of things.