Since the Salik gates remain active on Fridays and throughout the night, (when SZR usually carries only very light traffic), it's pretty hard not to come to the conclusion that this whole exercise was designed first and foremost as a cash cow. That being the case, when they see how many people are clogging the alternative routes, stand by for toll gates to appear on those other roads as well.
Fed up with outrageous rises in the cost of living in Dubai over the last few years, quite a few international companies have stopped posting senior staff to Dubai on a permanent, accompanied basis, but instead have them there unaccompanied for a few months at a time. This must have cost Dubai Inc a fortune in lost revenue already, (a lot more than might first come to mind, because the kind of people who aren't staying permanently and accompanied any more are from the high end of town, whose families used to inject a lot more into the economy than the average Joe like you and me).
If I may mix my metaphors unmercifully, Salik is just one more straw upon the proverbial camel's back towards the seemingly inevitable death of the Golden Goose the Dubai workforce is seen to be.