eBay is trying to attract a wider customer base.
The whole eBay Plus thing is a push to get more and more buyers into their net. Once committed to that membership, eBayers are more inclined to try to get the best possible value out of their membership fee by spending on eBay.
In the same way, eBay discount vouchers are sure to be shared by word of mouth, social media, etc. If eBay were to get together with a major advertising agency such as Clemenger or Leo Burnett or R/GA, etc., and plan an advertising campaign, can you imagine the cost? Really good advertising costs a huge amount, and frankly, eBay's advertising thus far is uninspiring and unimaginative.
Instead of paying for a first-class ad campaign, eBay's clearly funnelling funds into discount vouchers to the average eBayer, and funding postage and returns for eBay Plus members. They've already committed to a significant administrative cost in collecting the GST on behalf of ATO for low-value imported goods; they're surrounded by competitors (and those against whom they are but minnows trying to compete) and the answer - according to eBay's current CEO - is to massage the buyers, woo the buyers, make the buyers feel confidence in eBay.
It means spending money, but the upshot of it is that increased takeup of eBay Plus will pay for itself in increased sales (or so eBay are clearly thinking), and all of those eBay code vouchers will result in more sales as well.
