I think there is a time and place. Besides, there is no real way to enforce the terms of payments.
Also, I have made my own rule. After recently being taken advantage of on a p2 elder deal.
If somebody asks for me to declare an item as "gift" and lower value on the customs forms, then they MUST send payment as "gift". No exceptions. If you request an item is shipped as "gift" and lower value, then you also take the responsibility if something goes wrong.
That way responsibility is on the buyer for their request and they can't turn around and slap a paypal dispute on you (which happened to me).
That is a good way to protect yourself on these type of international transactions.
As a commerce mod - I get quite a few PMs of people needing help with transactions that have not gone well. I always tell people to never mark an item as a gift - unless you know the person very, very well or it is a low dollar amount like $5-$10.
I recently bought a RWOS and the seller asked I mark it as a gift. This seller had no feedback here so I was a bit worried since it was a fairly expensive piece. I said I was not comfortable marking payment as gift, but I would gladly pay extra to cover fees. I think I payed an extra $17. I also used a credit card for double protection...and the package was fully insured. To me, peace of mind, was worth the extra money. I want to know that if something goes wrong - I'm fully covered. Thankfully, the seller ended up being top notch and everything went smoothly.
Now as I buyer - I never ask anyone to send payment as a gift (unless it's for donations for a gift or charity - the less I have to pay in fees means more money for the gift or charity). For commerce transactions, I just eat it. Not a big deal - for an item around $100 it's $2.50. I can't even buy a latte with that and I want my buyers to be protected.
I don't like shipping internationally for a number of reasons. One, I will not mark the item as a gift and I will not declare a lesser value on the item. I sold an expensive piece to a Canadian and they were rather upset that they had to pay all these duty fees. I felt bad for them, but I was not going to screw myself over and lose a statue worth over $1000. Plus, the postal service is getting smart - I think if you are sending something worth $1000+ they are going to have a hard time believing it's just a gift.
Also - for large items it just REALLY sucks. Only certain carriers will take extra large boxes and then depending on the service you are eligible for, sometimes you can not get full insurance for expensive items. Then once the package is outside the US - tracking pretty much becomes non-existent...and once it is out of the country, many carriers say they are no longer responsible for what happens to the package in another country - if it switches over to a different carrier. Too much headache and worry - especially hoping the piece arrives in one piece and the buyer is honest and doesn't try to rip you off saying it was damaged or never received.
I would exhaust all avenues and sell in the states first. Then I would sell to Canada...but that's it for me. I have enough stress in my life...I don't need more.
But back to making new rules - doubt it will happen. We all encourage people to not pay as gift - yet so many people still do. It's up to each individual to do their homework and make sure they are not signing away their protection to save a couple bucks.