Probably because we've been around a while and know the "lay of the land". I do understand that customer retention and things like that are important, but I'm still not grasping what exactly the expectation here is. What product, anywhere on Earth, do you buy and expect updates? I'm not talking about just phones and tablets. I mean any product.
You buy a device, it does what you want. A year later it doesn't. You want the company to fix that, for free mind you, and not get anything in return from you. I think Samsung might have learned from the "mistakes" they made with the S3 and S4. The S3 got many of the features, or were promised them, as the S4 launched with. Many people viewed the S4 as a marginal update to the S3, and because the software tricks were coming to the S3, either kept their S3's or saved some money and got an S3 instead of the S4. Would they want to repeat that process with the tablets? Give a "free" update that effectively kills part of the market that would go and upgrade to the latest and greatest device. I put free in quotes because it's absolutely not free for Samsung to put the time and energy into getting the update ready, not to mention the cost of carrier certification for phones (not an issue with tablets). As I pointed out before, Samsung is a for profit company, so whatever they do needs to be justifiable to the shareholders as a way to turn a profit. It doesn't matter how much money they have in the bank, or whether or not they can afford it (nobody said that can't afford to do it), but the point is for them to more money in the bank, not less.