One thing I do find lacking is a discussion of assessing tradeoffs, particularly when her design principles bump up against natural pressures (i.e. driven by the market, not by fiat city planners). For example, she advocates a mix of new and old city buildings. Enforcing this may generate housing and office shortages, if a neighborhood becomes attractive at a rate exceeding that which we can maintain the desired old-new mix. How do we trade that off; at what price do we value incremental old-new mix?
She does cover some of this in her chapter on self-destruction of diversity, but her solution of zoning for diversity was a little tautological for me, just stating that diversity should be enforced. What I'm interested in is how we weigh that against the lost utility of individuals and businesses who would prefer to move to the neighborhood in question.
It's definitely a tough question! While I'd prefer some more head-on discussion of tradeoffs, I think (unfortunately, decades later) that there's still plenty of room for the ideas she advocates to be recognized at all.