It's a massive deal because the flexibility of computers is a massive deal. As it stands today, people can pretty much get what they want. By soldering a processor onto a mainboard, you are limiting the options available because it become too uneconomical to produce every combination. Think of it this way: let's say that you have a vendor producing 9 different mainboards and another vendor producing 9 different processors. You have 18 different products. With a soldered CPU, you would need 81 different products. With that many products, the less popular options would be trimmed off. Some people's needs would go unmet. (Incidentally, that is also a huge underestimate since both Intel and mainboard manufacturers produce many more models than that. I simply didn't feel like filtering out duplicate or obsolete models so I just used conservative numbers.)