score:46
From The Complete Works of Benjamin Franklin (published 1888), clipped from a letter to Charles Dumas, dated 6 Aug, 1781:
Some writer, I forget who, says that Holland is no longer a nation but a great shop and I begin to think it has no other principles or sentiments but those of a shopkeeper You can judge of it better than I and I shall be happy to find myself mistaken.
So we can see Franklin used the line, but doesn't take credit for it himself.
Concerning Why...
Perhaps the why can be gleaned by reading around the relevant lines. The National archives has records of these letters you can read, and in the section previous to the quote (emphasis mine):
...since the fixing of Mr. Adams there, I do not attend so much to the affairs of your Country as before, expecting indeed but little from it to our Advantage: For thoβ it was formerly in the same Situation with us, and was glad of assistance from other Nations, it does not seem to feel for us, or to have the least Inclination to help us.
Remember this is the middle of the revolutionary war, and the U.S. is attempting to secure a loan from the Dutch banks. The explanation is a little more bluntly put in the Next letter, of 12 aug 1781. It begins with providing news of the war, but then the second paragraph seems to apologetic concerning the content of the previous letter:
In looking over my last to you, I apprehend I may have expressβd myself perhaps a little too hardly of your Country: I foresee you will tell me that we have many Friends there, I once thought So too. But I was a little out of humour when I wrote, on understanding that no Loan could be obtained there for our Use, thoβ the Credit of this Kingdom was offered to be engaged for assuring the Payment, & so much is lent freely to our Enemies. You can best tell the Reason it will be well not to let my Letter be seen.
I am, ever, Dear Sir, Your faithful Friend, and humble Servant
B Franklin
So the Why was due to Franklins concerns over the inability to come to terms on securing a line of credit to finance the Revolutionary war.