It's all about generating 'buzz'. Getting people talking about the figures, having them chase them on ebay or having htem buying more than they otherwise would in hopes of finding the figure in a blind box. It's advertising to generate interest.
McFarlane sportspicks don't make anything extra off chase figures, but it gets people talking about them, positively or negatively.
UGH silver figures were the same with Hasbro last year. If we're talking about the toys, they have our attention, even if we're pissed off and mad as hell at them. That doesn't matter, we go to stores more often trying to find them, the scalpers buy them up that otherwise wouldn't touch the product.
Do I necessarily agree with it? No, but it's proven it's worth as a marketing tool time and again. I think utlimately it backfires on them as it has with TMP stuff, but that's not a consequence they seem to concerned about. Plus I think the notion of blind packed chase figures is pretty darn common in Japan.