More and more people are feeling short-changed after spending hundreds of dollars on device when there are no updates available after few months of their purchase.
In short that is simply a bad (existing) customer service on part of companies like Samsung, HTC, or Motorola and it will have to change in the near future as market will revolt against their products.
I use my DROID2 with Android 2.3.x on it and I did not feel that Ice Cream Sandwich is a must have for me at this time. All my app are written for backwards compatibility and after testing them positively on the newest Galaxy Nexus I decided not to buy it.
If Manufacturers start upgrading their devices I might start thinking about writing for the new features.