I guess Pioneer have to respond to the what the market is demanding. Another factor could be the fact that Pioneer will source their LCD panels from Sharp. It could well be the Sharp are planning to only manufacture 1080p panels in the future. It's all a numbers game with every company looking to outdo eachother which the latest features. Pioneer used to ignore the 'resolution race' and focus on quality but that, coupled with their desire to price themselves as a premium brand, hasn't got them very far. The change of direction was necessary for their survival.
I agree with you on the 1080p thing for normal TV viewing. However, more and more people are looking to buy a TV that can 'do everything' including functioning as a PC Monitor where having 1080p can be beneficial on smaller LCDs, especially if you are sat close. It's also one of the reasons that all the manufacturers are racing to give us more and more inputs - 4 HDMIs will soon be the norm.
I'm extremely happy with my 4280XD. It's ideal for what I use it for and I don't plan on upgrading for a few years. I had 'Upgraditis' with my laptop last years where I felt like upgrading every 6 months. I became obsessed with being 'futureproof' . It's always a losing battle. I will certain be interested in having a good look at the Pioneer LCDs when they are released - especially the 46" model but I don't think I'll be tempted to buy again until OLED tech becomes a more widespread technology.