As I understand it, the tax benefits of having your boat in an LLC accrue to the buyer of the LLC due to states not imposing sales taxes on the transfer of securities/membership shares. When the boat was originally purchased, even if purchased by the LLC, sales taxes on that purchase were likely paid, unless exempt for specific reasons such as putting it directly into charter. So the state got their sales taxes, at least on the initial purchase.
Part of the difference is that the tax on a used boat being brought into the state is a Use Tax, not Sales Tax. So different rules. I haven't tried it, but I doubt an LLC ownership will get you out of the tax.
Another thing to consider in all this is you state of residence. For those of you who are WA residents, the tax is immediately due when you bring the boat into the state. The visitor rules don't apply to you. And don't think you can place the boat in a non-WA LLC and come in as a visitor. They figured that one out and you need to show that none of the LLC owners are WA residents.
I agree with the sentiment that the taxes are part of boat ownership, but that only makes sense for a boat that's in the same place as your residence. I have bought numerous boats in MA where we live, for use here, and paid the tax and moved on, just like others are suggesting.
But it's different for a boat that is always moving. Should I pay tax like a resident everywhere I visit? If I had to, I wouldn't be visiting too many places. That's why all states have visitor provisions. Based on those provisions, I can decide which states to visit, and for how long, based on what it's going to cost me.
In this context, the challenges with WA are:
1) The tax rate is quite high at 8%-9.5%, and there is no cap. So tax in WA is roughly twice what it is in most other states, and in some cases 90% or more.
2) If you are in and out of the state, which is quite common, the rules become ambiguous, and you are suddenly playing a very expensive guessing game where someone else is making up the rules and not telling you what they are until it's too late.