People have tried. I knew someone who did a term paper on typesetting systems - wish I could find it - and the conclusion was basically "TeX sucks in a lot of w

People have tried. I knew someone who did a term paper on typesetting systems - wish I could find it - and the conclusion was basically "TeX sucks in a lot of ways, but the attempted replacements have always been worse." Knuth actually got a lot of things right and hence TeX's staying power.