For the collector, the answer is clear: history; technical interest; design that has stood the test of time. Furthermore, one can still purchase an old pen of great rarity and significance for less than the price of a heavily-hyped modern limited edition.
For the user, vintage pens offer this and more. Vintage nibs are often smoother and more responsive than their modern counterparts; more skilled labor went into finishing work back then, and nibs could be made flexible without fear that hands accustomed to ballpoints would destroy them (NOTE: our pen catalog has a special listing for pens with flexible, italic, and oblique nibs).
The materials of old pens are often superior, as well.Vintage Pens Plated nibs are very much the exception, solid 14K gold being the rule, and barrels and caps are typically made of celluloid a material unparallelled for coloristic effects, and now used only in a limited number of high-end European and Japanese pens. Where modern pens have components electroplated with a microscopically thin layer of gold, quality vintage pens use gold-filled parts with a layer of tough gold alloy thick enough that it can be engraved.