What you're saying is... in a nutshell... use % modifiers rather than flat rate +/- modifiers more commonly where crimes are concerned.
I dislike % very much
What i had in mind is to expand crime ranges up to whatever, new crimes(or rather crime severity) unlocked upon reaching certain city level 6/12/24/48.. The amount of crime could further influence severity unlocking even higher penalties at very high levels.
unlocked at 150 Crime (Black Markets I) city size 1-5
unlocked at 150 Crime (Black Markets II) city size 6-11
unlocked at 150 Crime (Black Markets III) city size 12-23
unlocked at 150 Crime (Black Markets IIII) city size 24
you could add more of them to take into account increased crime value, each new rank obsoletes rank below it or ads to it if that's not possible. Some crimes could be unlocked only by building certain buildings (Bank Robbery), also some buildings could have positive/negative bonuses for specific crimes (
DISEASES and POLLUTION) same way we get +1 culture from techs or some wonders modify certain buildings, this would work superbly for crimes and diseases, with each new building disease, crimes or pollution effects could grow stronger or weaker. This could apply to these effects themselves Drug or prostitution crimes could influence severity of diseases or add new levels to them.
No more level 200 cities before industrial age
EDIT:
lets not forget pollution here, its normal to have max lvl polution before you even hit factories, then it just takes of with no chances to manage it, unless you dont build production buildings, which makes new annoying problems like not being able to filter out pollution creating buildings, building filters not useful at all. Many just takes up place without providing anything useful >_<