Smartcoin is totally different from UIA.
Smartcoin is the real money, UIA is just a IOU.
For Example, if you have a UIA named A.IOU which backed by company A. as a user I can only cash out this IOU at company A. but if you have BITCNY you can cash out at Yunbi, BTC38 or Transwiser and so on. ..
absolutely IOU is very important to Bitshares to attract users, but smartcoin is our key competitive product, NXT also have good user experiences on IOU, but there's no other crypto project have smartcoin.