No its a bad move by manufacturers
The main issue with Nvidia doing this is that they have effectively provided a dual core processor based upon Google advising dual core processor support and enhanced tablet functionality in android 2.3 then you got Manufacturer posting that they are commited to next gen OS see link
To be fair though, cant really blame Advent (Dixons Group) for this as it isnt them causing the problem as they do offer continued support but there isnt anything they can do about Nvidia.
Google then backed out on dual processor support in 2.3 and released the single-core Nexus S to showcase Gingerbread.
So dual core is now set to arrive in 3.0 but then it seems either google effectively force manufacturers out of supporting tablet devices released over 1 month ago only taking the newest tegra devices(xoom,eee pad).
Or if it is Nvidia abandoning these devices? maybe if this is the case their mobile processors should be abandoned by us consumers if when buying an Nvidia powered product support can be cut so soon.
Anyhow android 3.0 will come to these devices one way or the other eventually (running 2.3.3 now on the Advent Vega but due to this issue without hardware acceleration which causes some video playback issues), it would just be nice if at least the hardware manufacturer would release the required drivers to allow the community to progress for at least 12 months or even release the source for the drivers. not too much to ask really is it.
If you went out and bought a new high end GFX card tommorow and paid £250 for it then next month windows 8 came out and Nvidia said naa not interested in ever writing drivers for that card ever again, Microsoft said no. Would you think ahh well it works on windows 7 fair enough.
I think NOT