I have 10gb of data allowed on my phone per month, and I go through a lot of it, if I had to store stuff in the cloud instead of on my sdcard, it would end up costing me a lot of money. We don't have unlimited data plans for mobile in Australia, well not that I am aware of.
Also some people don't like storing personal photos and video in the cloud. If you travel, it is easy to take photo and video and just swap out the microsd card for unlimited storage. wifi and mobile data is really bad in some countries.
I dont like excuses being made for the manufacturers, in my opinion they are doing it out of greed. The note 4 is not bulky at all in my opinion with the sdcard and removable battery, same goes for the lg g4, both phones show it can be done well.
Look what apple did with their mac mini computers. Their 2014 mac mini looked to have the same external dimensions as the 2012 model, but they soldered the ram into the motherboard, and I don't think you can easily change out the hard drive. Purely a move to get people to pay more for their overpriced RAM, or if you buy an older model and the ram is not sufficient you will have to buy a new one. I guess it is not an issue as most people will not care. And Apple can get away with it because they own ios/macosx, but samsung are not apple, they dont own android and there are a lot of other manufacturers that people can go to. They are already losing market share to LG, I reckon this move will see them lose an even bigger market share to them.
Microsoft has made a lot of blunders and miscalculations. They made horrible mistakes with mobile, and search engines, two very large potential income streams for them. And even with mobile, why do they persist with those tile icons. I know some people who use windows mobile say it is great, but it just hasn't worked for them given how low windows mobile market share is, they should change their home screen to the same as apple and ios. People go into a shop and look at those phones and it just looks too different to what they have all been accustomed to. They are making it easier for developers to port their apps to use with windows mobile, I think they should take the biggest apps and pay those companies to develop apps for their operating system. nokia/lumia produce some fairly nice hardware, but they are going to have to do something drastic to eat into apple/google market share.