Pens have long been used as promotional material
In fact, some businessmen, unimpressed with the way they were treated or the class of the wine would sometimes excuse themselves from potential business deals with reasoning along the lines of 'how can we trust you with our money if we can't even trust your choice of wine?' Of course, though that isn't to be taken literally, it highlights the point. In the same vein, giving personalized pens as corporate gifts also act as a valuable subterfuge, and is a nice touch to a business meeting. From my experience my company had two ways and instances when they'd give away personalized pens.
One instance, they'd giveaway personalized pens in an event, like a fundraiser or promotional debut for a service they just launched. What they do is buy nice, professional looking plastic pens in bulk, and have them printed with company names of the companies who would send their representatives over to the event. Of course, default branded pens have the host company's name, for individuals who represent no company. The recipients would normally be slightly impressed that their company is given due attention.
Another instance where my company goes about giving personalized pens as corporate gifts is when they give it through me, as their liaison. I'd meet with a very important partner or client company and discuss issues of substance, then at the end of the meeting, if all goes well, I present the representative of the other side his or her own personalized pen, inscribed is his or her name, as well as company. These pens are usually metal pens, and instead of print, laser engravings are used. Somehow these pens exude much more professionalism and executive aura than plastic pens. When I'm up to it, I even half-jokingly tell the other person how the metal pen symbolizes how our company wants our relationship to be: refined, beautiful, and strong as solid metal.
The second way my company uses personalized pens can be very expensive, as depending on the person they'd be giving it to, they can decide to buy pens worth more than hundreds of dollars and have them laser engraved. The point is, giving personalized pens as corporate gifts isn't new, and is quite effective. For small businesses growing into prominence, this small gesture will almost inevitably turn into a sort of trick of the trade.