I think the reason why most times many kills and deaths is regarded as being worse, is more often than not at nearly any level of play, most deaths could have been avoided. It may be something like being over-extended without vision, or maybe trying to save a nearly guaranteed lose for some of the deaths but still often either mechanical mistakes, or miss-positioning leads to most deaths at nearly every level of play. This is why people often tell you at any level of play there is still room to improve.

However in lower kills and deaths games, you usually either played really safe, or you just weren't ahead enough to get multiple kills. So often people regard it more positively.

In terms of actual impact on the game, I think a large component of what matters most is the gold and level difference you have in comparison to your opponents, be it off kills, cs or just exp from zoning as well as on what champion you have this. Champions that generally scale better into the late game benefit more from equal gold distribution vs opponents than poorly scaling or early spiking champions.