Older boats have a track
record that newer boats do not. With older boats you can look up their
reliability over time and make a more educated decision. Newer designs are more of a crapshoot. It's not that new designs are better or worse, there is more of an unknown to them.
Also, the market for used boats is very soft and the chances of finding a
used boat in excellent condition that has taken the big depreciation hit from its original cost is excellent.
In many places there are more boats than there are slips to put them in. This drives up the cost of berthing which makes owning a boat less desirable, which drops the demand for owning and therefore the value of a boat.