I'd say practice is key. A nice welder helps, sure but I'd say most of it lies with the person over the gear. I have good equipment, I am not using the pulse feature on my welder where you can get a very consistent weld pattern from. I am trying to develop my hand welding skill and I have seen marked improvement in a short span of time. Already I see improvement just doing this project.
however,
Many people are hyper critical of welds, how they look. I went to the Smithsonian in December and saw the Apollo 15 rockets and your BMX nerd/keyboard cowboy would scoff at the welds on the rocket engines that took men into space. So being someone who had made lots of bikes through the years I'm not so critical, but there is the expectation of perfection of how a weld looks and it is a silly thing that people have chosen to hang onto and point out over and over again while having never done anything themselves... Understanding that I have to meet that expectation regardless of how absurd and ignorant of a stance it is.