Integrating transit media with debit-credit card functions could be very expensive for the rider
CTA's Ventra debit option rife with fees" (also see the 2012 piece, "New fare card set for CTA, Pace: Commuters on CTA and Pace will have the option to pay their fares with a new card, called Ventra, starting next summer").
The fee to reload a debit card from a credit card seems steep and unnecessary. (I wonder if you could get around it by using Paypal.)
The monthly dormancy fee is high too. Many states have legislated against such fees being levied against gift cards.
Plus, why don't they co-brand the Ventra Card with the CTA logo-brand?