It is actually a mispeling of "'it wood pleas Smee too know 'enned", from the pirate legend, of course. My research did turn up some cases of the "too" being dropped but I think we can all agree that such a phrase doesn't really make any sense in the context of the legend.

I think I'll switch to "it would please me long time" to avoid confusion / controversy.

Before doing the research that turned up the pirate legend origin, I too thought "I've never heard 'it would please me no end'" but thinking on it more I realized that I had heard that version just not much recently.

And I really think the reason for the shift is a combination of "it would please me no end" having an awkward feel when you try to parse it grammatically (as you noted) and people finding "to no end" familiar (even though with a different meaning, especially since that other meaning is rather idiomatic anyway). So it can be more comfortable to say "it would please me to no end" when you aren't thinking about it, which is usually the case when someone utters a pat phrase. Just like it is easier to say "I could care less", avoiding that awkward "nt" sound that interrupts the flow of the phrase.