Of course it's a form of marketing! And so are written notes are a form of marketing of inks, and I find it fascinating, how they find ways to promote themselves and their merchandise without annoying ads, email etc. Yes, unfortunately they manage to do it also without sales, but hey, you can't have everything.
And when you say you prefer to give up on candies (which my son wouldn't agree with) and fancy wrapping (which I wouldn't agree with, because I live overseas, and I saw what bad packaging can do to a parcel), you say it as a current customer, who bought from them many times and get used to this stuff. A new customer who makes his first order gets blown away by all that small things, just because he never see this kind of stuff in any other online store, and yes, in online shopping personal touch matters.
Don't get me wrong, price matters too, that's why when I shop for Jinhao's I go to AliExpress, because prices are lower three-four times and I get free shipping (which in the case of GP I pay more, then for the pen itself). But when I buy something worth investing, the difference between GP and other retailers aren't that different usually, so I prefer to support those guys over saving $5-$10/