My subscription to Wizard101 is expired and I won't be renewing, the only reason why I would renew would be to play new areas I haven't been at yet and PvP is so unfun in Wizard101 that I won't be playing. If however I could get into the newer end areas for free to see if they are enjoyable I'd possibly be privy to spending money for a another renewal.
When it comes to Pirate101, I go to the test realm to try out different companions, equipment, and the like to see if they are worth buying on the live realm. See that is the thing, I test everything out on the Test Realm to make purchases on the Live Realm.
If you have new players and they don't know if its worth it to them to spend money for membership for new areas or areas they don't have, then as a pre-purchase option they should be able to go to the test realm to entice them or not to spend money on the live.
The current system of the test realm being for subscribed members only is in my viewpoint costing KingsIsle a lot of potential players and sales. Sure its nice that new players can play for a short while for free in the free to play areas, but allowing them full access on the test isn't going to hurt anything after having so much on the live realm that it takes forever to get through it all. Even if a free player tries to complete the entire game on the test realm their account is going to be wiped. The live realm is where you play that is free of being wiped out, while the test realm should exist to let players see where they want to spend money or if its worth it to them to spend for the permanent live realm.
I think both Wizard101 and Pirate101 test realm should become free to play. To complete Wizard101 on the test realm would take months of 24/7 play.