I think that there are objective measures of complexity. So there are objective measures of simplicity.
ideographic writing is more complex and less composable than phonetic writing and yet can express the same ideas.
Subjectively, a chinese can understand Chinese ideograms while maybe he find written English difficult to understand. But a Chinese would learn phonetic writing in less time than ideographic writing and would be capable to express complex ideas using the most composable writing system in less time, no doubt.