Couple points.
Maybe $4/oz seems good to some, but that's $64/lb. That's in the realm of SG bulk and other "premium" tobaccos. For comparison, a pound of 1Q or RLP-6 is $27.50. Maybe MD uses slightly better tobaccos, more expensive sauces, etc. but there's no way it's twice as much.
I understand only selling their non-aromatics and english blends in 1.5oz tins because they age and mellow. Aromatics don't. In spite of that, english blends like Sunrise Smoke and Blend No. 5 are offered in 8oz tins.
The "average" pipe smoker settles on a couple blends and buys them by the pound ( http://pipesmagazine.com/blog/put-that-in-your-pipe/post-show-reflections/ ) whereas most of us "hobbyist" smokers like to have multiple blends open for variety and we're constantly trying new things. It makes sense for us to buy 1.5oz, 2oz, and 50g tins. Based on that, it seems Sutliff only wants to market and sell these blends to the hobbyist. If they offered it in 8oz tins or even bulk, I'm almost positive they would sell more.
I don't buy the "we don't sell enough" response. Maybe they don't sell enough because it's only offered in 1.5oz tins so customers looking for better value than $4/oz buy something else. It's definitely popular enough to be offered in a larger or bulk format. It's the only Sutliff blend with its own jump-site/mini-site. http://sutliff-molto-dolce.com/ I couldn't find one for Maple Street, Blend No. 5, or Sunrise Smoke...all blends that are offered in 8oz tins.