The Macbook Pros sold today do not allow HD upgrades. (I'm not sure about ram.) I doubt they will last as long as my current one has.
Something I do like about my MBP, even after quite a few years of abuse it still looks in decent shape. The case, screen hinge and keyboard all still feel solid. Which is where lots of other laptops seem to fall apart. Though the battery and trackpad have seen better days. Something nice about macs is they are usually serviceable for quite some time, either via Apple or third parties - I needed a new power adapter recently and could walk into a shop and get a new one there and then. Trying to track down power adapters etc for short lived models from other manufacturers can often be a pain.
All in all I don't think it's anything magic about macs. If you bought a similarly specd and built machine from someone else you'd be in the same position.
I like the thinner profile of the Retina, the much upgraded internals, and 16GB RAM, but it's just not worth the sacrifice in onboard storage. At least until there's a reasonably affordable way to have a cloud-based Lightroom workflow.
I believe the RAM is soldered onto the motherboard for all newer Mac models.