Many things are going to a closed architecture. Automobiles were previously 100% user-serviceable, but not anymore. Televisions had tubes that could be replaced, but not anymore. If the Surface Pro specifications do not meet your needs due to RAM, SSD or battery, there is nothing else currently on sale that will meet those needs. The Lenovo Helix and Kupa Ultranote are the only two with superior specifications, but both are vapor right now.