Kodak is a publicly owned company. However they operate their business, their responsibilities lie primarily with the shareholders, and decisions are made in accordance with that. You can argue that they might not have done a very good job of making those decisions, but that's the truth. Either there is enough profit in a product, or there isn't. If there isn't, it gets chopped.
Ilford is, as far as I understand, a privately owned venture. Their responsibilities are counted differently. Yes, they still have to make profit, but they have only themselves to be held accountable to. So it's OK for them to hold onto a low volume film, if they feel there are other reasons than profit to keep it. I don't know the numbers, but I'm sure Ilford make the bulk of their profit selling HP5+ and Delta 100, rather than SFX and Delta 3200 - but they still keep all those market lines, and my own wild guess is that they do it to have a complete market line, hopefully satisfying most of the darkroom photographers out there, instead of only those that bring the most profit. Looks good in the customers' eyes, you know.