I'm sorry to see you feel this way Chaos, certainly mainland values have dropped, however, so have RL real estate values!
I've found that buying and selling mainland has always been a very competitive business, and unfortunately not everyone who does this is honest. The same can be said for buying and selling islands. However, I have also found that the great majority of people I have dealt with are honest and I've had very few problems in the past four years.
I am still amazed that people abandon their land, mainland or islands, maybe they are angry and just don't care, however, to give their land away for 0L$ makes no sense to me.
When you give land away, you are not taking profit away from LL, in the case of mainland you are giving money to LL, and with an island I've yet to see one not sell for more than 395usd with a full month's tier.
Granted if someone paid a lot for land and now can't get much for it they would be mad, but still it seems to me that a person might as well get something instead of nothing?