Worth depends on ur budget. No matter what you will be better spending a 100 more on a VGA than on ram or on a better display or on a better sound system, unless you have enough budget to buy all without problems.
TBH One could simply buy a monster VGA and then a mid-tier system and play at 4k with the GPU max out @ 60FPS, it wont be a balance system but it will let you play with higher image quality. I for one prefer a more balance system but this kind of system has its advantages also(you can simply sell ur MoBo and CPU and buy new ones w/o much spending to keep updated with new tech while VGA tech have longer life time, so you could still have a system with all the new stuff every few years and you could just need to buy a new VGA from time to time.