They raised the limit in 3.3 (June 2016) so it's now level 35 and you can have 300,000 gil:

[2.0] The following adjustments have been made to the free trial version of the game:
The level cap has been raised from 20 to 35.
The maximum amount of gil players can carry has been increased from 100,000 gil to 300,000 gil.
SE need to update their document linked above, it just causes confusion. But yeh it's pretty restricted still. No retainers, no market board, unable to form a party (you can be invited) or trade items at all... I can't realistically see a lot of people wanting to stay trial for longer than they have to. Now they just don't have to worry about rushing to see what the game is like.