I don’t expect to do a lot of theme revisions, don’t want a lot of complex features, so having basic page options (various column set ups, etc.) and typographic and spacing control are most important. I will generally set up a child theme to change colors, typefaces, etc. Certainly some complexity/detail work/lots of stuff I don’t know about is needed for security issues, and I rely on WordPress and themes for much of that, and plug-ins, but other than that, simple (and hence inexpensive for theme makers to create) works for me!