Better GPUs are not used because "details look better on them". They all are capable of displaying same visuals. Level of details depends on game settings, and you can pretty much choose high or ultra settings on any GPU and it will show the same quality of visuals (provided it is capable of doing so - you cannot use a 20-year old GPU with modern games because it will not support latest direct x, for example, and it won't even run the game).
The problem is, slower GPUs will struggle with high settings and will produce low number of frames per second (fps) which will be percieved as huge stuttering, lag and eye strain.
1080 is immensely more powerful than 550, and such GPU can be used to max out details in any game up to 1440p...