Expecting a small degree of preferential treatment for being a frequent flyer is not being elitist. It is the fundamental basis of any loyalty program: give CO all your business and CO rewards you with perks (arguably...)

Non-elites in premium seats is not the issue. The issue is that when all of the window and aisle seats are taken and only middle seats are left, the non-elites should be required to fill up the middle seats in the non-premium area before the middle seats in the premium section are assigned. It is not elitist to expect that as a loyal frequent customer. Once the middle seats in the rear are taken, then non-elites would start filling up the middle seats in the front. A middle seat in the front is no better than a middle seat in the back. But why should an elite be stuck with a pax in the middle seat when first time flyers in the rear have empty seats next to them?